Despite the grim subject throughout the film, in an interview on the second disc of the Criterion Collection box set, actress Hélène Surgère claimed the mood was actually rather jovial on the set and that none of the teenage actors were actually harmed or traumatized. She said the abundance of teenagers who had never acted before led the mood to be happy and at times, even fun, with the cast often playing practical jokes on each other. She also said that the movie was literally "made" in the editing room and the filmmakers had no idea how grim a movie it was until they saw the finished product at the premiere.
Pier Paolo Pasolini was murdered before the film's release. A 17 year-old hustler, Giuseppe "Pino" Pelosi, was arrested when he was found with Pasolini's car. He admitted running over Pasolini several times with the car after an argument, and end up convicted of the crime. Many years later, he denied participating in it, claiming that three mysterious men were involved. The case remains unsolved.
Salò is a town in northern Italy which Benito Mussolini's Fascist government effectively made their capital from 1943 until they fell from power in 1945.
Ennio Morricone, who composed the jazzy soundtrack, said he was very uncomfortable watching the movie. He only agreed to score the film due to being friends with Pasolini.