(at around 1h 5 mins) In the scene where Bella goes to the Cullens house for the first time, when Nikki Reed's character had to break the bowl, she actually cut her hands. This is why she is wearing gloves for the scene in the film.
(at around 1h 11 mins) Robert Pattinson actually plays the piano in the scene where Edward is playing "Bella's Lullaby".
Nikki Reed was the one who got the producers to add Robert Pattinson's songs to the film. Reed secretly started recording him from her laptop, while he was singing and playing his guitar in filming breaks. She then took it to the director and producers, where they fell in love with his songs. The next day, they asked Rob if he could record a few of his songs for the soundtrack, and he reluctantly accepted.
As soon as Robert Pattinson was cast, he moved to Oregon and began working on his character, both physically and mentally. He worked out five hours a day with a trainer: learning to fight, play baseball, and do stunts. He also had to learn to drive and get an Oregon driver's license.
Robert Pattinson stated in an interview that this is his first American role and he had no formal training to perfect his American accent.
Stephenie Meyer: (at around 1h 12 mins) The author of the original books can be seen next to a laptop ordering a vegetarian sandwich in the diner at the beginning of the scene where Charlie asks Bella if she likes the boys in town.