When Stu is being told to "hang up the ****ing phone" by the prostitute played by Paula Jai Parker, she calls him the 'N' word. This was ad-libbed, so the who-do-you-think-you're-talking-to look that Colin Farrell gives her after she says it is genuine.
During the movie, when the Caller warns Stu not to move, he says "You can get shot 41 times just for pulling out your wallet". This is a reference to the killing of Amadou Diallo, an innocent man who matched the description of a serial rapist. The police approached him and he pulled out his wallet (presumably to show them his ID), they mistakenly thought it was a gun and the four officers on scene fired 41 rounds at him. He was shot 19 times and died as a result of his injuries.
Screenwriter Larry Cohen originally pitched the concept of a film that takes place entirely within a phone booth to Alfred Hitchcock in the 1960s. Hitchcock liked the idea, but he and Cohen were unable to figure out a plot reason for keeping the film confined to a booth. Once the idea of a sniper came to Cohen in the late 1990s, he was able to write the script in under a month.
The movie was originally set to be released on 15 November 2002. However, after the sniper attacks in Maryland, Virginia and Washington, D.C., 20th Century Fox decided to delay the release of the film.
Jared Leto was in the film, playing an actor in a theater production of "Drockula". He and Colin Farrell's character have a quick scene in an alley. The scene was deleted from the film, but restored when the film was aired on television.
Larry Cohen worked on the script for the movie Cellular (2004) while he tried to get his screenplay "Phone Booth" sold. In a New Yorker article, he says he wrote "Cellular" with the intention that it would be the direct opposite to "Phone Booth" ("Phone Booth" is about a man trapped on a phone in a booth, while "Cellular" is about a man who is still trapped on a phone but can go anywhere). However, his friends told him that he had written the same screenplay twice.
The phone booth is supposedly on the north side of West 53rd Street between Broadway and Eighth Avenue. The filming began there but it was already November 2000 and much too cold for the cast and crew. After one day, the shoot took over in a historic section of downtown LA on 5th Street. It looks like NY, save for the well-known Studio 54 and Ed Sullivan Theatre which are on the original location's block.
According to writer Larry Cohen the movie was turned into a stage play in Japan in 2009. He never attended a showing (because "he doesn't understand Japanese so he wouldn't have understood it anyway") but to his knowledge it ran successfully for 4 or 5 months.
The rifle on the tripod in the sniper's window is an Accuracy International Rifle. Accuracy International is a British firm that manufactures dedicated sniper weapons as opposed to offering modified hunting rifles like many other companies. The price of the setup in the movie ranges from $6000.00-$9000.00 dollars depending on what kind of scope was mounted.
The original ending was that Stu would step out of the phone booth and start firing up at the windows. Then after Stu lets off 2 shots, the Rubber bullet from one of the snipers hits him, he goes down. Ramey steps into the phone booth to get the receiver, hearing on the other line, the SWAT team coming in the door, and wounding the "voice." The Script ends when Ramey wants a final statement from the Voice and he says, (directing to Stu) "But you'll never forget me. I gave you the most thrilling day of your life. Say thanks." Then he dies.