Okay, go to the part when Jack Black first enters the classroom. He asks the kids if they have any food, and one of the little crumb snatchers raises her hand. Jack Black opens her desk and finds a hoagie sandwich and eats it in front of the class. He's holding it in his right hand, the camera switches from Jack to the class a few times. First the sandwich has been eaten down to the top of his hand, then the camera switches and comes back, and there's about two inches of the hoagie above the hand. Then the camera switches back, and its half eaten again. Either there's been some obvious editing, or it was intentional; one or the other.