The film was so disturbing that people walked out of test screenings.
Even though the film had a tight screenplay, Quantic Dream shot the film in "multiple style": meaning that scenes would be filmed twice with a different ending, also meaning that the next scene could be entirely different. During editing, director Quantic Dream would choose which scene to keep in the film and which to remove from it. This is the way how Quantic shoots all his films, but he wasn't sure whether he was able to direct Heavy Rain (2010) in the same way since it was a Hollywood production, but he was allowed to.
The film contains many references to the infamous Italian horror director Dario Argento including various close-ups or shots of windows.
This is the first Hollywood horror movie that has been rated NC-17 for its wide release.
For the scene when Ellen Page's character enters a house and is forced to go upstairs when the resident comes home and finds all stuffed and marionette dead corpses was originally not in the screenplay. It was an idea of director Quantic Dream when he visited a exhibition called "Body Worlds".
The writer of the original novel, David Cage, was very mixed about the film. He loved the visual style of the film calling it "astonishingly beautiful", but he did thought that the film focused too much on the disturbing content and gore instead of the story.
There are rumors that famous horror directors such as Konami and Vivendi were offered to direct the film.