Continuity mistake: When Bella is in the hospital, in the close-up of her face, the breathing tubes are right by her eyes, but when the shot is farther from her face, the tubes are on her cheeks.
Continuity mistake: When Bella gets out of Edward's car after Port Angeles, she leaves her purse behind and goes home with her father. At home, she has the book she bought at the store and put in her purse that she left in the car.
Continuity mistake: When leaving from the baseball scene, Emmett's jeep goes from being dirty on the sides with mud from the tires, to being clean.
Revealing mistake: When Bella sees Waylon's body being gurneyed onto the ambulance, Bella has a flashback of Edward's eyes being black. In the short snippet, you can see the rim of the contacts he's wearing.
Plot hole: In the last scene with Victoria, she's looking through the window at Bella and Edward at the prom. But if they were at such close proximity, Edward should have heard Victoria's thoughts, as he does near the end of Twilight: Eclipse.
Continuity mistake: In the hospital, after the 'almost' car crash when Edward saves Bella, she has a blood pressure cuff on her arm. You can see the nurse take it off. She has it off for a while, but then it reappears on her arm in one shot, just as her dad says "you can kiss your licence goodbye".
Continuity mistake: When Bella enters Biology class and talks to Eric about the prom, she starts to walk, then pauses to look across the room towards Edward. In this shot, the Armadillo is not on the shelf, only what looks like a peice of paper is hanging there. The Armadillo appears on the shelf only after she has sat down at her desk and Edward moves the microscope towards Bella saying, "Ladies first".
Continuity mistake: After Edward saves Bella from being crushed by the van, while he is holding her, Bella's hair is outside of her jacket covering up her hood. When the shot changes her hair is tucked beneath the jacket and the hood is visible. When the shot changes back, her hair is covering up her hood.
Continuity mistake: When the Cullens are in the garage preparing to take Bella to safety, Edward closes the trunk lid twice. First time is not so obvious because the camera is on Emmett and Rosalie, but the trunk closes on the right of the screen. Then it shows it closing again with it being the main shot.