Behind-the-scenes network politics embroil television executives responsible for late-night programming after 1991's retirement announcement of Johnny Carson (played by Rich Little) from The Tonight Show on NBC.
Carson's permanent guest host Jay Leno (Daniel Roebuck) and the host of the show that follows Carson's each night, David Letterman (John Michael Higgins), both vie for the position. It is widely assumed that Letterman is the hand-picked heir apparent Carson favors, but privately NBC executives speculate that Leno could be more popular with 11:30 p.m. audiences, as well as easier for the network to deal with and control.
Leno's tough manager Helen Kushnick (Kathy Bates) secures the spot for Leno with negotiating tactics that could be construed as either shrewd or unethical. Leno is concerned that her methods might alienate Carson but does not wish to be disloyal, as he believes Kushnick to be responsible for his success and had promised to take care of her after her husband's death. She harshly instructs the comic to just keep telling jokes and leave the business end to her.
Surely enough, she lands Leno the coveted job as Tonight Show host and the producer's position for herself, on the condition that no public announcement will be made. Letterman continues to believe he is still in contention for the position. Another reason NBC's executives prefer Leno is that they will own the show, whereas Letterman stipulates that he will maintain ownership rights to his.
Kushnick's bullying manner angers Leno's bosses, colleagues, potential guests, and others to the point of interfering with network airtime and relationships. The top NBC executives warn the mild-mannered Leno that they are going to fire Kushnick and, if he sides with her, he would be let go as well. Kushnick is dismissed by NBC and barred from the studio lot. She keeps pleading with Leno to keep his promise to take care of her and her daughter, but he is angry because she nearly cost him a dream job. Leno eavesdrops on a private executive meeting in which they discuss the possibility of having Letterman step in as host.
Letterman, devastated at being passed over, hires Hollywood superagent Michael Ovitz (Treat Williams) to negotiate on his behalf after Ovitz makes the dramatic promise that not only will he ensure Letterman is offered an 11:30 p.m. show, he will be offered it by every network. True to Ovitz's word, Letterman is courted by all the major networks and syndicates. He continues to hold on to his lifelong dream of hosting The Tonight Show, but Tonight Show/Late Show producer Peter Lassally (Steven Gilborn) makes it clear that the Tonight job is now "damaged goods" and that he would be working with the very people who passed him by, who may also double cross him and retain Leno if he can make the show a hit before Letterman takes over. Letterman is still unconvinced, so Lassally suggests he call Carson to ask for advice. Letterman asks Carson what he would do in the same situation, and after Carson says he would probably leave NBC, Letterman accepts a lucrative offer to host his own 11:30 show on CBS.
Letterman and Leno ultimately go head to head at 11:30, with Letterman winning in the TV ratings in the beginning, then Leno firmly re-establishing his show's lead in the ratings.
Real life CBS executive Rod Perth (played by Ed Begley Jr. in the film) appears briefly in a cameo role. (He’s the man Howard Stringer mistakes for Perth in the CAA lobby). Actor Ed Begley Jr. and Rod Perth share an extraordinary physical resemblance, something the film makers milk for humor in the scene.
The film received seven Emmy Award nominations in categories including "Outstanding Made for Television Movie," makeup, casting, writing, directing, and acting. For her role in the film as Helen Kushnick, actress Kathy Bates won awards from the American Comedy Awards, the Golden Globe Awards, the Satellite Awards, and the Screen Actors Guild Awards. The film was also recognized with an award for "Outstanding Directorial Achievement in Dramatic Specials" from the Directors Guild of America Awards. However, David Letterman, who saw clips of the film, called the movie "the biggest waste of film since my wedding photos." He also likened John Michael Higgins' portrayal to that of a "psychotic chimp." Letterman invited Higgins onto his program, but Higgins declined.
Kushnick filed a $30 million lawsuit against Bill Carter, author of the eponymous book upon which the HBO film was based, claiming libel. Specifically, her case related to a claim that she planted a story about Carson's retirement in the New York Post. The then-pending lawsuit was noted in the film's epilogue, as the Broadway tune "There's No Business Like Show Business" plays. The lawsuit settled out of court for an undisclosed sum; Kushnick died of cancer in August 1996.
On January 19, 2010, during Conan O'Brien's final week as host of "The Tonight Show," guest Quentin Tarantino jokingly suggested that he direct a sequel to The Late Shift, cast O'Brien as himself and make it a revenge movie in the style of his film Kill Bill with the title Late Shift 2: The Rolling Thunder of Revenge. The Toronto Star reported in February 2010 that a sequel to The Late Shift film was in planning stages. In the final episode of The Tonight Show with Conan O'Brien, O'Brien stated he wished that actress Tilda Swinton could portray him in a film version about The Tonight Show conflict, referring to a running gag about their similar appearance. Swinton subsequently expressed interest in being cast as Conan O'Brien in a sequel to The Late Shift.
When asked in a June 2010 interview with Movieline if there was going to be a film adaptation of The War for Late Night, Carter responded that plans were not serious at that point, stating, "Not really. Nothing serious. Let’s put it this way: There have always been people kicking it around because they think it’s funny. ... Letterman made a ... joke saying that Max von Sydow should play him. So, you know, people are just kicking it around like that." Actor Bob Balaban, who portrayed NBC executive Warren Littlefield in the film The Late Shift said he would like to portray Jeff Zucker, and stated actor Jason Alexander would also be a good choice to play Zucker.