- Acting in the Dark: Karen Allen was never shown a complete script before she worked on this film. William Friedkin deliberately kept her in the dark, since her character Nancy wasn't supposed to be aware of what was happening to Steve as he explored the gay underworld.
- Actor-Shared Background: Di Simone mentions his wife leaving him and moving down to Florida with their young daughter to live with his wife's sister. In real life, Joe Spinell's wife, porn star Jean Jennings, divorced him several weeks before he filmed his scenes and moved to Florida—exactly as his character describes.
- Banned in China: The film was banned in Finland, Iran and South Africa.
- Deleted Scene/Missing Episode: William Friedkin's original cut was 140 minutes long. Friedkin claims he took the film before the MPAA board "50 times" at a cost of $50,000 and deleted 40 minutes of footage from the original cut before he secured an R rating. The deleted footage, according to Friedkin, consisted entirely of footage from the clubs in which portions of the film were shot and consisted of "[a]bsolutely graphic sexuality....that material showed the most graphic homosexuality with Pacino watching, and with the intimation that he may have been participating." In some discussions, Friedkin claims that the missing 40 minutes had no effect on the story or the characterizations, but in others he states that the footage created "mysterious twists and turns (which [the film] no longer takes)", that the suspicion that Pacino's character may have himself become a killer was made more clear and that the missing footage simultaneously made the film both more and less ambiguous. When Friedkin sought to restore the missing footage for the film's DVD release, he discovered that United Artists no longer had it. He believes that UA destroyed the footage.
- Looping Lines: Some scenes had to redubbed due to gay rights protesters disrupting filming by making lots of noise.
- Name's the Same: This is a movie about a detective named Steve Burns, but it has nothing to do with Blue's Clues.
- Unintentional Period Piece: The film is very much a time capsule of a bygone era in gay life; a year after its release, the first reports of AIDS-related illnesses were reported in New York City.
- What Could Have Been:
- Brian De Palma really wanted to direct this film but his producers could not obtain the rights to the material, so he made Dressed to Kill.
- William Friedkin originally wanted Richard Gere for Steve Burns, because he believed that Gere would bring an androgynous quality to the role. Robert De Niro was offered the role.
- Paul Morrissey was going to direct with Jeff Bridges as Steve Burns and Jan-Michael Vincent as Stuart Richards.
- James A. Contner originally wanted to shoot the film in black and white, as he felt it would fit the look of the S/M world.
Trivia / Cruising