Trivia: In the scene where Alice finds Bill's body hanging on the back of the door to the generator room, the producers purposely did not tell Adrianne King what they were going to do to the body nor did they let her see the body beforehand. When she saw the body during filming it was for the first time. The scream she produced was genuine as it scared her badly. Needless to say, that entire scene was shot in one take.
Trivia: A sequel to The Long Good Friday was written by screenwriter Barry Keeffe. Entitled The Black Easter Monday, the action starts immediately after that of The Long Good Friday when the car carrying Shand is stopped by police. Both Shand and the IRA gunman (played by Pierce Brosnan in one of his first film roles) bluff their way out of it and walk away, allowing Shand to escape. The screenplay was universally acclaimed but by the time it got through development hell Brosnan, Bob Hoskins and Helen Mirren had all become big stars. They could not commit to the project and their salary demands could not be accommodated anyway. The film was never made.
Trivia: This film's ending mirrors that of "Carrie," another film that this movie's director, Brian De Palma, made; at the end of "Carrie," Susan Snell has a dream of visiting the wreckage of Carrie White's house. Then Carrie's hand pops out of the ground and grabs Sue's arm. Susan wakes up screaming and is comforted by her mother. This film ends with Liz having a nightmare about Robert escaping from the institution, coming to her home and killing her. Liz wakes up screaming and is comforted by Peter.
Trivia: Writer-Director John Carpenter appears in the film as Bennett, Father Malone's assistant, at the beginning of the movie.
Trivia: The line "It's not who you go with, it's who takes you home" is said in every Prom Night movie, even despite the fact that the later films aren't true sequels to this one.