Continuity mistake: In the scene where they are driving up to the police station there is only one bright orange paper taped to the door, however close up there are three (orange, blue, black). Also a potted plant mysteriously appears - when they are driving up in Edward's car you can see there is no plant on the porch and when Carlisle comes out there is.
Continuity mistake: At the beginning, when Bella and Charlie first start talking in the patrol car, they stop at an intersection. Through Charlie's window we see a young man walking toward the four way about to cross the street and there is no traffic approaching. In the next shot, there is a rig carrying logs crossing the intersection in front of the patrol car, and the young man is nowhere to be seen. (00:02:35)
Continuity mistake: In the scene where Bella and Jessica are outside enjoying the strangely sunny day, there's a boy in a brown shirt sitting in a table behind them. As they are talking, that boy remains seated, but when the shot changes from a close-up of Bella to a two-shot, the boy is suddenly standing up. (00:37:20)
Continuity mistake: Different vampires have white faces but their ears and necks are normal color in different scenes.
Continuity mistake: On Bella's first day of school, when Eric comes up and introduces himself, Tyler passes them, going the opposite way, and looks at Bella. But in the last scene he was sitting at his car, making no move to leave, let alone go back to the parking lot. (00:06:25)
Revealing mistake: When Bella and Edward are identifying the different stages of mitosis (prophase, metaphase, anaphase) in the lab it's not possible given the position of the microscope lens in relation to the microscope stage. The lens is positioned too far from the stage for an image of the nucleus to be correctly focused in the ocular. (00:16:55)
Continuity mistake: Rosalie's roots go from visible to not visible in different scenes.
Continuity mistake: At the prom Edward gives Bella a glass in her right hand, in the next shot beckons Bella to Eric and Angela with the right hand. When camera goes back the glass has vanished. (01:45:20)