Kristen Stewart received her high school diploma by correspondence one week before filming Bella's graduation scene. She took a mock graduation photo with an extra so she'd have a photo of herself graduating high school.
Originally, the scene where Jacob carries Bella to mask her scent, Taylor Lautner was to push Kristen Stewart on a cart. But it did not look real enough. So Taylor agreed to carry Kristen himself. Only after so many takes, his arms were extremely sore as they filmed the scene all day.
In the stories that Billy Black tells at the bonfire, the third wife was originally going to be played by Kristen Stewart. She did perform the scene but the director David Slade and author Stephenie Meyer thought it had an unintentional comical effect.
(at around 7 mins) The note Bella retrieves from her drawer that happens to be from Jacob is actually the same note that is used as the prologue of the 'Eclipse' novel. Just as in the novel, lines of text are scored out rather than erased.