In "Part I: The Darkness Inside - Chapter Seven: The Million Dollar Question" & "Part III: Waking Up from the American Dream - Chapter Seven: Love Hurts", the player can interact with the pianos to play part of the games theme music.
Contributed by ProtoSnake
There is a secret room in Chapter 7, "The Million Dollar Question." When walking on some scaffolding, following the ledge past the first open window will reveal a second open window. Inside this window is a small shrine with a memorial for Miika Forssell, a developer who died during the development of the game.
Contributed by gamemaster1991