The soundtrack was recorded by a full orchestra at Abbey Road Studios in London.
In one of the Behind the Scenes videos Jacqui Ainsley is seen while auditioning for Madison. The dialogue she read for Madison explained that while on assignment in the middle of war zone a terrorist attack took place and she felt responsibility since she was powerless to stop it. This would have explained to the player Post Traumatic Stress Disorder was the cause of her insomnia, but the monologue is not in the final version of the game.
A lot of scenes that fleshed out Madison were cut out. Scenes planned would've involved helping her redecorating her apartment (which looked different than in the final version). It was also planned that the newspaper she worked for was going to be a major set piece which would get multiple visits so she could do research and write her articles. It also would've established why she suffers from insomnia, which was because she had been a war corespondent.
90 actors were cast for the game, which uses motion capture to produce life-like animation.
Several episodes of downloadable content (that explored the past of the protagonists) were planned, but only one was ever released: Heavy Rain: Chronicle One - The Taxidermist (2010), which featured Madison Paige. Future chronicles were put on indefinite hold to focus on adding Playstation Move support to the main game. It is highly unlikely that any more chronicles will be released.