In the scene where the main male character Bob Nolan escapes from prison, two other prisoners briefly appear. One of them is in fact the Argentinian director Gaspar Noé.
The song heard repeatedly during the movie is "Samoa tamourè" sung by the band "4 + 4 di Nora Orlandi".
This is the main song of the Italian movie "I mostri" by Dini Risi released in 1964.
In the film, there is a character named Charles Meatson with a cross on his forehead, which is obviously a reference to Charles Manson.