Trivia: Val Kilmer has been quoted as saying that screenwriter Kevin Jarre insisted the actors wear real wool costumes, in accordance with the time period. During the scene in the Birdcage Theater, Val Kilmer says, a thermometer was placed on the set, and it read 134 degrees Fahrenheit. Kilmer suggested jokingly that this was the reason Doc Holliday killed so many people: "It's just, like, he wore wool in the summer, in the Arizona territory, and that made him mad."
Trivia: Johnny Depp was unhappy about the fact that he spoke negatively about Darlene Cates (Mama) while he was in character as Gilbert; he would frequently and sincerely apologize to her between takes.
Trivia: Just something interesting, Brendan Fraser makes a guest appearance in the beginning in Crawl's room during the Halloween party. He is the same character he played in Encino Man.
Trivia: At the end of the film when Christian Slater and Patricia Arquette are on the beach, the kid playing their son is Patricia's real-life son.
Trivia: Paul McGann plays both Girard (the man out to revenge his sister's honor) and the Cardinal's Guard who is killed by D'Artagnan out by the city ruins.
Trivia: When Molly crashes the cab, you see the advertisement on the top of the cab reads "Senor Pizza." This was the name of the pizza place in the movie Loverboy, which Kirstie Alley was in.
Trivia: Director Oliver Stone has a cameo as the man who tries to convince the reporter that the president is not the same man as he used to be.
Trivia: The Assassin is a remake of a French movie, La Femme Nikita.