Continuity mistake: After the Grinch unscrews the light bulb in the town Christmas tree, all the lights in the town go dark and the Grinch starts to take off in his sled-thing. When they show a close up of him, the lights are on. Then a few seconds later, the lights are off again.
Continuity mistake: Allie's brother asks their dad (who just finished pitching the "bones for bowsers dot com " idea to Sam) "How long are you gonna be gone this time." He raises and lowers the hands in the same shot, and in the next the hands are raised again. (00:03:15)