The first thirty minutes of the film has a background sound with a low frequency of 27 Hz which is almost infrasonic (this sounds like a rumble/vibration), similar types of noises are at times used by police to stop riots. According to Gaspar himself, this could only be heard in theaters (which usually have huge sound systems/subwoofers) and not from headphones or regular home theaters. In humans, this noise causes nausea, sickness, and vertigo. It was one of the reasons people walked out of screenings during the first part of the film. In fact, it was added by Thomas Bangalter (from the electronic music group Daft Punk) to get this reaction.
After the film's premiere in Cannes, the audience sat in almost complete silence until the next movie was scheduled to start.
Gaspar Noé says he had no idea how long the rape scene was going to last. That was in the hands of Monica Bellucci and the actor playing her assailant. He said, "The results were great the first day, but even more perfect on the second. The actors were more and more confident with each other and so they could go further and further. I didn't know if it would last for six minutes, 10 minutes, 12 minutes or whatever. The whole scene was in her hands and even the guy who was playing the rapist was at her service. If she didn't want to do the scene like that, she would have said it. I really admire her for having taken that scene so far."
Monica Bellucci and Jo Prestia completed 6 takes of the rape scene in over two nights, three times each day. They took breaks of 2 hours to 2 hours and a half between each take. Bellucci claimed the first take was actually the easiest to do since on subsequent takes she had an awareness of what was going to happen and had to prevent this from interfering with her characterization.
Director Gaspar Noé only had a three-page draft before the movie was shot, so all of the dialogue was improvised.