Walter Hill initially wanted a Puerto Rican actress for the role of Mercy, but Deborah Van Valkenburgh's agent convinced the film's casting directors to see her and she was eventually cast.
Ajax was originally conceived as a tall, muscular, physically imposing figure. Character actor Irwin Keyes was strongly considered for the role however Hill, deciding Keyes was too old for the role, opted to go with the smaller yet wiry James Remar. Keyes was given a consolation role in the film as Hill cast him as the NYC cop who hits Ajax with his club after Ajax is caught in the park sting operation. So Keyes got to arrest the character he was originally considered to play.
Big Name Fan: Ronald Reagan was a fan of the film, even calling Michael Beck, to tell him he had screened it at Camp David and enjoyed it.
Beam Me Up, Scotty!: It's not "Warriors, come out and play!" It's "Warriors, come out to play!"
Breakaway Pop Hit: Joe Walsh originally co-wrote and recorded "In the City" for this film. When he re-recorded it on the Eagles album The Long Run a few months later, it became a staple of rock radio (though it was never actually released as a single).
Cast the Expert: Many of the extras and supporting bit parts were played by real-life gang members.
Cast the Runner-Up: Irwin Keyes was strongly considered for the role of Ajax, but James Remar was cast instead. Keyes was cast as the cop who arrests Ajax in the sting operation.
Dawson Casting: With the exception of Rembrandt, the gang all look like they're at least in their mid-twenties (Michael Beck was actually 30), but Fox mentions that they have a youth worker. Swan and Mercy are also compared to a group of kids coming from prom. These suggest that the gang is supposed to be in their teens.
Disowned Adaptation: Sol Yurick, the author of the novel, liked Walter Hill's direction of the film, but wasn't pleased with the many changes to the story, the slightly Lighter and Softer tone of the film compared to the novel, and Roger Hill's performance as Cyrus, who Yurick didn't think came across as a realistic gang leader.
Dueling Movies: Released the same year as The Wanderers with both films sparking discussion about youth gangs. The studios raced to beat each other to the punch, but The Warriors came out first and had the more lasting impact.
McLeaned: Thomas G. Waites (Fox) was fired eight weeks into principal photography, for being difficult and arguing with Walter Hill, so his character is removed from the movie when a cop throws him into the path of a train during a fight. To this day, Hill has felt bad about the rough times he had with Waites. Waites is not in the final credits because he demanded that his name be removed. However, he did return to reprise the role in the game.
Role Reprise: Dorsey Wright (Cleon), Michael Beck (Swan), James Remar (Ajax), David Harris (Cochise), Thomas G. Waites (Fox) and Deborah Van Valkenburgh (Mercy) all return to voice their characters in the game.
Sequel in Another Medium: There's a comic book that follows up on the events of the film. It received a sequel titled Jailbreak by Erike Henriksen which addresses Ajax's fate. Both were published by Dynamite Comics.
Walter Hill realized that the scene where Luther and the Rogues confront the Warriors at Coney Island was missing something, so he asked David Patrick Kelly to come up with something for his character to do. Kelly recalled a crazy man from his youth who would taunt him by shouting, "Come out to play!" so he ad-libbed the lines. He originally requested dead pigeons to hold in his hands, but the production couldn't come up with that, so he substituted clinking the beer bottles in his fingers.
Ajax's James Remar ad-libbed his line, "I'll shove that bat up your ass and turn you into a Popsicle!"
Uncredited Role: Thomas G. Waites (Fox) demanded that his name be removed from the credits.
An opening narration was planned, voiced by Orson Welles. It's included on the director's cut DVD, along with comic book-style transitions between scenes.
A real-life gang leader was cast to play Cyrus, but mysteriously disappeared shortly before principal photography.
If Hill wouldn't have been able to make this movie, his backup plan was to do a western film called Last Gun.
The story was originally set in Los Angeles.
Originally, it was Fox who was supposed to be the sympathetic character whom Mercy goes with in the end. The director and the actor playing Fox had a falling out, so Fox gets hit by a train. Furthermore, Vermin was supposed to die at the hands of the Lizzies, but his actor was likable enough that the director decided to spare him. Swan was supposed to be kidnapped by a gang with a penchant for anal rape, but escape and return for the final showdown.
Snow was originally named Snowball and did not say a single word until the end when he gave a small statement about how they should fight the Rogues to avenge their fallen friends.
Tony Danza was set to play Vermin, but chose to star on the sitcom Taxi, instead.
Tony Scott tried to get a remake off the ground for several years, which was ended by his suicide in 2012.
The Video Game
The Other Darrin: While this is averted for the most part, Luther, Vermin, and Cyrus (except for his iconic speech) were all recast for the video game. Rembrandt's actor had died in 1985 due to complications from AIDS.
Screwed by the Lawyers: The Playstation 4 re-release omits In The City by The Eagles in favor of a generic instrumental. This is a particularly egregious example since In the City was only used to match up to the end of the films credits.
Possibly. In the arena mode, two of the stages are at the graveyard the Warriors regroup at after Cyrus is shot. They are the only stages not present in the actual levels. In one mission you can overhear a conversation between a group of Jones Street Boys, and sometimes they'll talk about a time The Warriors screwed them over in the graveyard, which is mentioned nowhere else in the game. It seems that at least one additional level was planned, but scrapped for whatever reason.
A spiritual sequel (unrelated to the film) was planned by Rockstar. The game was to be titled We Are the Mods and was to be set in 1960s England during the mods and rockers brawls.