The time is the 1890s. Captain Sam (Henry Travers), owner of the showboat River Queen, travels along the Mississippi River bringing honest entertainment to each town. At a stop in Ironville, he meets Crawford (Alan Curtis), Bonita (Rita Johnson), and Bailey (Joe Sawyer), who are wanted by the local sheriff. Against the advice of his daughter Caroline (Lois Collier), his lead actor Dexter Broadhurst (Bud Abbott), and his chief roustabout Sebastian Dinwiddle (Lou Costello), the Captain joins them for a card game at a local gambling house.
The Captain is plied with alcohol until he is intoxicated and gets involved in a crooked card game where he loses controlling interest in the show boat to Bonita and Crawford. They turn the showboat into a floating gambling casino with every game rigged in their favor. Dexter and Sebastian help the captain regain ownership of his vessel and oust the unwanted criminals.
The line, "Who's on First?", was ranked No. 91 on American Film Institute's 100 Movie Quotes. The "Who's on First?" routine was intended to appear much earlier in the film. Costello begins the routine by saying, "When we get to St. Louis...", but at this point in the film they are already in St. Louis. The camera crew can be heard laughing in the background during the routine.
The film also contains the "Lower/Higher" routine, where Costello auditions as a singer while Abbott shouts directions to the stage crew to change the height and placement of the backdrop curtain. Costello believes Abbott is directing him, not the stagehands, and follows Abbott's instructions by singing higher or lower, or even on one foot.
Bonita sneaks poison into Lou's wine, leading to the old swapping of glasses routine (previously done by Abbott & Costello in Pardon My Sarong).
Costello accidentally bakes feathers into a cake, which is served to everyone in the saloon. The patrons wind up coughing up a blizzard of feathers. This gag was taken from the Three Stooges short Uncivil Warriors (1935).
Costello and Sawyer perform the "Mirror Scene," copying each other's actions. Variations of this old vaudeville routine were done by several movie comedians, most famously in the 1933 Marx Brothers film, Duck Soup. Abbott and Costello had used it before, too, in Lost in a Harem.
To break up the crooked card game and rescue Captain Sam, Abbott concocts a plan to dress as a bear and scare everyone out of the casino. Costello ends up wrestling with a real bear, thinking that he's wrestling Abbott in a bear suit.
Filming occurred from January 15, 1945 through March 1, 1945. On May 13, 1945, during filming of their next film, Abbott and Costello in Hollywood for MGM Pictures, Abbott and Costello returned to Universal for re-shoots on this film. The riverboat used was originally constructed for the 1936 Universal musical Show Boat.
It was re-released in 1950 along with One Night in the Tropics, which also contained a shorter version of the "Who's on First?" routine.
This film has been released twice on DVD. The first time, on The Best of Abbott and Costello Volume Two, on May 4, 2004, and again on October 28, 2008 as part of Abbott and Costello: The Complete Universal Pictures Collection.