Continuity mistake: In the first biology class, when Edward moves the glass petri dish over to Bella and "hides" one in his hand, a piece of paper is lying crooked between them on Bella's side of the table. In the next shot, both glass dishes are between them, and the paper is on Edward's side, and it's now vertical. (00:10:30)
Revealing mistake: In the hospital after the car accident, we are first introduced to Carlisle. If you look at his face you can see where the white face makeup doesn't meet his hairline. Patches without makeup can be seen.
Continuity mistake: When Bella enters the biology classroom and Edward has finally returned, as she walks over to her desk the large book sitting on the edge repositions itself from sitting horizontally to vertically between shots. The bit of paper above it also moves closer to the edge. (00:16:10)
Visible crew/equipment: When Edward first brings Bella to his house, as he is leading her upstairs he stops on the bottom step and turns to her to talk. In this shot you can see the faint reflection of the long microphone pole moving up and down in the glass siding of the staircase. (01:01:30)
Continuity mistake: When the Cullens are in the kitchen making Italiano for Bella, Rosalie is holding a crystal bowl that Emmett has filled with salad. But when Edward tells them Bella has already eaten, just before Rosalie shatters the bowl, the bowl is half empty, and only a few lettuce pieces fall to the floor amongst the crystal shards. (01:04:30 - 01:05:05)
Continuity mistake: When Charlie is sitting at the table cleaning his rifle and Bella is talking to him, he places the cleaning rod (with the green handle) down on the table. In each different shot the rod is in a different place, either hidden behind the collection red ammo or not. (01:14:10)