During the scene in the mall when the girl is in the dressing room, she keeps putting on more layers of clothing. But as they are shooting different shots she will have a hot pink shirt on, then it is back on the hanger, and then back on again. It switches back and forth many times.
In the scene where David And Orlando lead the class into the crater to see the meteor on the field trip if you pay attention to the background actors you can see a young John Cho. (Harold from Harold and Kumar).