When the three boys are sitting in Principal Doppler's office telling him what happened to them by Filkins, he is leaning against the door. He walks in and a person with a checkered shirt (Ronnie?) is walking in following behind him, but then disappears from the scene.
When Wade approaches Brooke during lunch there is a girl in a pink top sitting next to Brooke. In the next cut the girl in pink is no longer sitting there. There are two other girls sitting on the opposite side of the table as Brooke so that Wade can sit down.
When Wade and Ryan are practicing fighting in the garden, Ryan punches wade in the back and Wade puts his right arm on his back. When Ryan tells wade to punch him, his left arm is now on his back and he punches with his right arm.
Filkins' car doesn't have a front plate, which all cars in the state of California are supposed to have. This could simply be an addition to his long list of misdeeds.
When the Tiger Services bodyguard is being interviewed and puts his hand in the cup of coffee from another table, the smoke moves out of the cup and down, although real coffee smoke/steam would just go up.
When Wade's parents enter the living room to see what was stolen, the window is intact, even though Don had broken it earlier when he was robbing the house. There is no way there was enough time to fix the window in time.
Fire sprinklers operate independently and it requires heat to activate a fire sprinkler and only the sprinkler closest to the fire goes off not the entire school.
When the three boys go under the already closing garage door to get away from the two bullies, the garage door should have automatically re-opened, assuming the safety sensor was working correctly. (about 22 minutes)
When Drillbit is talking to Don about going to Canada, he says that a ticket would cost roughly about $287, he'd have to throw in $50 for bribing the Mounties and a good winter jacket would cost about $80. He said that the total cost would be $387 all together, but if you add up the cost of the bribe and jacket, which is a total of $130, to the cost of the ticket, $287, the total cost would be $417, not $387.