The scene where Lars and Bianca are about to enter the party was entirely improvised by Ryan Gosling (Lars), as well as the scene where he performs CPR on Margo's teddy bear.
In the scene where Lars is reading to Bianca, he is reading from "Don Quixote," whose main character also has delusions.
To help Ryan Gosling stay in character, the real doll was treated like an actual person, as is done by the characters in the movie. She was dressed privately in her own trailer and was only present for scenes that she was in.
Extreme sensitivity to touch is a form of hyperesthesia.
Ryan Gosling brought in a Talking Heads cassette to play during the filming of the party as he thought it would be cool for the scene.