Set in 1905 (the year the Little Nemo comic strip premiered in the New York Herald), the film opens with the young boy Nemo experiencing a nightmare in which he is pursued by a locomotive. Upon awakening the next day, he goes to see a parade welcoming a traveling circus. However, Nemo is unable to see the circus because his father and his mother are too busy to take him. Later that night, Nemo imitates sleepwalking in an attempt to sneak some pie away, which acts against a promise he had made earlier to his mother. Upon falling asleep that night, Nemo is approached by figures from the parade. The circus organist introduces himself as Professor Genius and claims that they had been sent on a mission by King Morpheus, the king of a realm named Slumberland. The mission involves Nemo becoming the playmate of the princess, Camille. Although Nemo initially has reservations about interacting with royalty of the opposite gender, he decides to set off to fulfill his mission after being persuaded with a gift box of cookies from the princess.
Nemo is taken to Slumberland in a dirigible which he is allowed to drive, causing some chaos and is introduced to King Morpheus, who doubles as the circus ringmaster on Earth. Morpheus reveals that he summoned Nemo to become his heir to the throne. Morpheus gives Nemo a golden key that opens every door in the kingdom and warns him of a door with a dragon insignia that must never be opened. Nemo is introduced to Princess Camille and the pair roam the entirety of Slumberland together. Afterward, Nemo meets the mischievous clown, Flip, who angers a group of cops and forces him and Nemo to hide out in an underground cave. There, Nemo discovers the door that Morpheus warned him not to open. Flip tempts Nemo into unlocking the door, which unleashes the dreaded Nightmare King. Nemo rushes back to Morpheus' castle in time for his coronation ceremony, where Nemo is handed the royal scepter, the only thing capable of defeating the Nightmare King should he ever return to Slumberland. In the middle of a dance session between Morpheus and Genius, the Nightmare King reaches the castle and steals Morpheus away. As the partygoers search for a scapegoat, Flip reveals that Nemo was responsible for the Nightmare King's escape, since Morpheus gave him the key.
Nemo awakens in his home, which floods with seawater and ejects him into the ocean. Genius discovers Nemo and tells him not to blame himself for all that has happened. When the two return to Slumberland, Flip reveals that he has a map to Nightmare Land, where Morpheus is currently being held. Nemo, Camille, Flip, and Genius set off in a tugboat in search of Morpheus. They are soon sucked into a whirlpool and find themselves in the monster-infested Nightmare Land. The four come across a group of shapeshifting goblins who wish to aid in the quest to find Morpheus. The Nightmare King sends a flock of frightening giant bats to seize the rescue party. Nemo attempts to use the scepter, but awakens in his bed instead. The goblins appear in Nemo's room and the group travels to Nightmare Castle by flying through a hole in the sky. However, they are subsequently imprisoned in the castle, where the Nightmare King demands possession of the scepter. Nemo soon uses the scepter to finally eliminate and defeat the Nightmare King. Slumberland celebrates the fall of the Nightmare Kingdom. Camille escorts Nemo home on dirigible. The two share a kiss after which Nemo awakens in his room, where he apologizes to his mother for breaking his promise and trying to take the pie. Nemo's parents also agree to take Nemo to the circus. Nemo stares out the window as he reflects on his adventure.Gabriel Damon (Takuma Gōno in the Japanese adaptation) as Nemo: the protagonist. He is a human boy living in New York City who is taken to Slumberland to be the official playmate of Princess Camille; in actuality, however, he is being summoned to be the heir to the elderly King Morpheus. He is given the key to Slumberland, but is warned by the king to leave a door with a coiled dragon emblazoned on it closed. Sadly, he opens the aforementioned door when he is tempted by Flip and goes on a quest to restore Slumberland to its rightful glory, save King Morpheus and defeat the Nightmare King.
Mickey Rooney (Chikao Ōtsuka in the Japanese adaptation) as Flip: a supporting protagonist. Described as a "frightful fellow" by Professor Genius, he is wanted throughout Slumberland for "having fun" (the bounty on his head is a sizeable one) and his only friend is his partner-in-crime: a bird named Flap. He tricks Nemo into accidentally releasing the Nightmare King and blames him for the ruin of Slumberland. He is in possession of a map of Nightmare Land (hand-drawn and written in his own special code) and serves as the guide to the Nightmare Castle until he is replaced by the Boomps. He has a serious smoking addiction. In the real world, he is a clown in a circus that stops in Nemo's town.
René Auberjonois (Kōichi Kitamura in the Japanese adaptation) as Professor Genius: King Morpheus' advisor and a supporting protagonist. He comes to the real world to bring Nemo to Slumberland. A sophisticated man, he is quite punctual and prefers order as opposed to madness. He is quite a dancer, as he dances quite a bit during Nemo's coronation ceremony. In the real world, he is an organ player in a circus that stops in Nemo's town.
Danny Mann as Icarus: a flying squirrel, Nemo's best friend and a supporting protagonist. Icarus is Nemo's only friend from the real world. He shows great concern for Nemo's wellbeing in a sense similar to that of two siblings. He speaks a mix of both squirrel and some English. His screech is painful to the ears of the Boomps. He detests being called a "little rat" (which Princess Camille mistakes him for). Unlike other squirrels, Icarus eats human food, like cookies. His initial relationship with Princess Camille, though rough, eventually changes for the better.
Bernard Erhard (Kenji Utsumi in the Japanese adaptation) as King Morpheus: the elderly ruler of Slumberland and a supporting protagonist. He has protected Slumberland for years with the help of the royal scepter: an ancient weapon of great power. Though he is a child at heart, he knows when to be serious. He has Nemo brought to Slumberland so that he may become his heir to the throne. He gives Nemo the key to Slumberland, which can open any door; however, he warns Nemo of one door with a dragon symbol emblazoned on it that must never be opened. Like Professor Genius, he is quite a dancer, as he dances alongside the Professor during Nemo's coronation ceremony. When Nemo accidentally releases the Nightmare King, King Morpheus is captured and Nemo has to go and rescue him from Nightmare Land. In the real world, he is the ringmaster of a circus that stops in Nemo's town.
Bill Martin (Tarō Ishida in the Japanese adaptation) as the Nightmare King: the main antagonist. He is a demonic creature who was locked behind a massive door until he was accidentally set free by Nemo, who was given the key to the door by King Morpheus. Once free, he captures King Morpheus as revenge for his imprisonment and then retreats to the Nightmare Castle. When Nemo goes to the castle to save King Morpheus, the Nightmare King has his minions capture Nemo's friends (Professor Genius, Flip and Princess Camille). He is shown to be quite temperamental, as he destroys several minions for the failure of just one of his underlings (the general of his army). The only thing that can defeat him is the legendary royal scepter.
Laura Mooney (Hiroko Kasahara in the Japanese adaptation) as Princess Camille: the daughter of King Morpheus and a supporting protagonist. Though she initially acts somewhat spoiled, she eventually grows to like Nemo. She also grows fond of Icarus (and vice versa, despite a rough start). When her father is kidnapped by the Nightmare King, she takes over as ruler but decides to join Nemo in his quest to save King Morpheus. In the real world, she is the daughter of the ringmaster of a circus that stops in Nemo's town.
Greg Burson (Tesshō Genda in the Japanese adaptation) as Nemo's father and Flap
Jennifer Darling (Mari Yokō in the Japanese adaptation) as Nemo's mother
Neil Ross (Hiroshi Ōtake in the Japanese adaptation) as Oompa
Alan Oppenheimer (Keiichi Nanba in the Japanese adaptation) as Oomp
John Stephenson (Masaharu Satō in the Japanese adaptation) as Oompo and the Dirigible Captain
Sidney Miller (Kōzō Shioya in the Japanese adaptation) as Oompe
Michael Bell (Hiroko Emori in the Japanese adaptation) as Oompy
Kathleen Freeman (Kimie Nakajima in the Japanese adaptation) as the dance teacher
Bever-Leigh Banfield (Seiko Nakao in the Japanese adaptation) as the woman
John Stephenson (Kazumi Tanaka in the Japanese adaptation) as the dirigible captain
Bert Kramer (Yukimasa Kishino in the Japanese adaptation) as a goblin: A hideous creature that serves as a member of the Nightmare King's army. They are sent by the Nightmare King to ensure that Nemo doesn't reach his castle and free King Morpheus. Though the goblins succeed in capturing most of Nemo's friends, they fail to capture Nemo himself and, when the Nightmare King finds out, he kills them all in a fit of rage. The only goblins to survive are the Boomps (who, in contrast to the other goblins, are not hideous and are actually friendly).
Beau Weaver (Tarō Arakawa in the Japanese adaptation) as a policeman
Sherry Lynn as Bon Bon
Guy Christopher as a Courtier and a Cop
Nancy Cartwright and Ellen Gerstell as pages
Tress MacNeille as an elevator creature
Michael McConnohie as an etiquette master
Michael Gough as a teacher
Michael Sheehan as a fencing master
June Foray as the librarian
Gregg Berger as the equestrian master
Nemo was the brainchild of producer Yutaka Fujioka. His dream for years had been to make a feature length, animated film version of Little Nemo in Slumberland which would utilize the resources of his Tokyo Movie Shinsha studio. As the first step towards realizing this project, in 1977 he personally flew to Monterey, California to convince McCay's descendents to allow him to obtain the film rights to the comic strip. He originally approached George Lucas in a year later to help produce the film, but Lucas found problems with the storyline, feeling there was no character development for the titular character Nemo. Fujioka also approached Chuck Jones, but Jones also declined. The film was officially announced as a project in 1982. In February of that year, the company TMS/Kinetographics was formed in America to produce Nemo, and the best staff from around the world were gathered together to begin production. Gary Kurtz was appointed producer of the American production side and hired Ray Bradbury and later Edward Summer to write screenplays. Kurtz would eventually step down in the fall of 1984.
In the early 1980s, both Hayao Miyazaki and Isao Takahata were involved with the film, but they both parted ways because of creative differences; essentially, Miyazaki did not seem to be keen on the concept of an animated feature created by him where everything was a dream, and Takahata agreed with Lucas and was more interested in creating a story depicting Nemo's growth as a boy. Miyazaki later described his involvement on the film as "the worst experience he has ever been through". The directors who succeeded the duo were Andy Gaskill and Yoshifumi Kondo, whom both exited production in March 1985 after completing a 70mm pilot film. Osamu Dezaki was also brought into direct at a brief point and too completed a pilot film, but left as well. A third pilot film was made by Sadao Tsukioka but has yet to become publicly available.
Brad Bird and Jerry Rees also worked on the film through the American department as animators for a month, while at the time were also working on an unproduced adaptation of Will Eisner's The Spirit with Gary Kurtz. During production, the two would regularly ask animators what they were doing, the response they were commonly given was "we're just illustrating what Bradbury is writing", upon meeting Bradbury in person and asking him about the story he was writing for the film, he replied "I'm just putting in writing what these wonderful artists are drawing". Bird and Rees soon left the project after their meeting with Bradbury.
When all of these people had left, Fujioka had drafts done by Chris Columbus, Mœbius, John Canemaker, and many others. He then re-hired Summer to do yet another screenplay. Subsequently, Richard Outten was hired to work from Columbus' screenplay while Columbus was busy with his directorial debut, Adventures in Babysitting. Many Disney Studio animators including Ken Anderson and Leo Salkin worked on individual sequences, and John Canemaker, Corny Cole, and Brian Froud provided visual development. Frank Thomas, Oliver Johnston and Paul Julian consulted to the production. The world-famous Sherman Brothers (Richard M. Sherman and Robert B. Sherman) were hired to write the songs for Nemo. This was their first anime film, though not their first animated film; the pair had previously worked on several projects for Disney, including The Jungle Book and Hanna-Barbera's Charlotte's Web.
Little production progress was made until January 1988, when the many ideas pasted on the walls of the Los Angeles studio were whittled down in order to create the storyboard from which the film would be made. It was at this point, Thomas and Johnston recommended William T. Hurtz as the director of the American production side and TMS hired Masami Hata, a former Sanrio film director, as the appointed director at the TMS studio in Japan. Actual animation for the completed film was commenced in June 1988, as TMS was just completing Akira. The success of that film in Japan further helped TMS finally start production on Little Nemo. Even though it derived from an American comic strip, Little Nemo was animated by the Japanese company Tokyo Movie Shinsha and thus is often considered an anime film, even though it was a joint production of Japanese and American animators and production companies.
The Japanese cut was released in Japan on July 15, 1989. In a Summer that included strong competition, including Studio Ghibli's Kiki's Delivery Service, which was ironically directed by one of the animators who left the production of this film, it grossed ¥0.9 billion ($10 million USD) in its release and was considered a box-office flop, against a budget of around ¥3 billion ($35 million USD).
The English dub was released three years later in the United States in 579 theaters on August 21, 1992 through Hemdale Film Corporation. 11 minutes were cut in order to secure a G rating.
It received mixed to positive reviews from publications including The Washington Post, Variety, the New York Post, the Boston Globe, and The New York Times. Roger Ebert gave it 2 out of 4 stars, though on a positive note wrote, "Little Nemo is an interesting if not a great film, with some jolly characters, some cheerful songs, and some visual surprises."
Despite having a positive reception, the film failed to find an audience. In its opening weekend in the United States, Nemo made about $407,695 with a total US gross of approximately $1,368,000. It won the "Audience Award" at Amsterdam's 1992 Cinekid Festival and was nominated for "Best Animated Feature" at the 1993 Annie Awards.
In March 2005, Little Nemo was given a very limited re-release in Denver, Seattle, Atlanta, Austin, Houston, and other cities in the US. This was through Regal Entertainment Group's Regal Cinemas, Edwards Theatres, and United Artists Theatres as part of a Kidtoon Films family matinées promotion. It was only shown on weekends.
After the film's release, Fujioka decided to retire from the animation business. TMS, having to recoup Little Nemo's losses, increased production on locally based anime programs and became highly involved in animation for western-based productions, including Tiny Toon Adventures, Animaniacs, and Batman. Since the early 2000s, TMS has no longer supplied animation services to western studios due to increasingly demanding costs. The studios has never again attempted a project like Akira or Nemo. The studio still does features, but primarily films spinning off existing anime properties, which include the likes of Anpanman and Detective Conan.
The film was released on VHS through Hemdale Home Video, Inc. on March 2, 1993. It features a mail-in coupon worth $5.00, with purchases of Tropicana Orange Juice. Hemdale also produced a Collector's Set which includes a VHS movie, illustrated storybook, and cassette soundtrack. Nemo became the #4 best-selling children's title of 1993, with 1.5 million copies sold.
On October 5, 2004, Little Nemo was released on DVD through Funimation (under license from TMS, which had regained North American rights to the film after Hemdale closed). All of the cuts that were made in the 1992 release were restored in this DVD, bringing the run time of the film to the full 95 minutes, even though it would receive a PG rating. However, this is not mentioned or addressed in the DVD materials.
After the title went out of print, Little Nemo could be seen selling anywhere from $80 to $200 US for a sealed copy (usually DVD) on Internet sites such as Amazon and eBay. Funimation's DVD was re-released as a budget title from Echo Bridge Home Entertainment on January 27, 2009, appearing commonly in department stores in low-price bargain bins. Then after Echo Bridge's reissue went out of print, it was released again by Discotek Media. On November 6, 2012, Discotek released a Blu-ray of the film containing the Japanese dub and original English audio tracks and included bonus features such as the pilot films from 1984 and 1987.
After the Japanese release, but before the US release, Capcom developed an NES game titled Little Nemo: The Dream Master, which was released in late 1990. An arcade game, also by Capcom, was developed that same year under the title Nemo.