Continuity mistake: In the restaurant scene when Olive is on a date with Anson, after the waitress sets their food down on the table, Olives bib begins changing positions between shots. In one shot it is tied around her neck. In the next, it appears tucked into her shirt down on her chest. The bib goes back and forth several times before she finally takes it off.
Other mistake: In the beginning of the movie, when she is speaking to the viewers on her web cam, Olive says something about whatever book you're reading in class always relates to whatever teen drama you have going on, except Huckleberry Finn. As most of the movie is in flashback, this scene takes place chronologically near the end of the story. However, in one scene shown later (ie. before the webcam comment), a girl runs up to Olive and say something along the lines of, "Did you hear about Brandon? He left his parents a note that says, 'I'm gay, bitches!' and ran away with some hulking black guy!" and Olive says, "My apologies to Mark Twain." In the film continuity Olive's comment makes no sense, as she hasn't referenced Huckleberry Finn yet. And/or her webcam comment is out of place, as at the time she makes that comparison she now knows that even Huckleberry Finn is relevant to teen drama.
Continuity mistake: In the scene where Olive and Anson are sitting in the cafeteria talking about going to the Lobster Shack, once Anson stands up, watch the girls in the background. You see a grey sweatshirt and shorts go by, followed by a blond and curly dark haired girl. Then, once the camera shifts and comes back, you see the same curly dark haired girl, followed by the blond and the grey sweatshirt girl.