Continuity mistake: When Calvin is sitting in the seat which has elastic ropes attached to it, he jumps forward to grab the grandfathers food. When he grabs the sausage, which is the last thing he eats, there is a slice of lemon on the plate, but when the grandfather looks down there is no slice of lemon. You can see this without stop motion, but it's much clearer when you do pause it.
Visible crew/equipment: Early in the movie, in the scene where the 2 guys steal the large diamond, the 'little man' (who is black, and wearing black gloves) cuts a hole in the wood around the diamond, using power tools. In the shot where he replaces the wood (after taking the diamond), you can very see a white, gloveless hand in the bottom left (near the drill hole) is putting the piece back in place.
Continuity mistake: At the hockey game, the girl has 4 full cups of beer. She gives one to Darryl and his 2 friends, and the guy sitting beside Calvin. When she turns around, there's one full cup still on the tray.