Continuity mistake: In the car, Candy is spraying on hairspray with one hand and her other hand is styling her hair. In the next shot, the previously empty hand, which was styling, now has a pink mirror in it.
Continuity mistake: At the beauty shop, the little purple bows on Candy's red tank top disappear.
Visible crew/equipment: In the scene where the car gets stuck in the giant donut, the thick black steel bars holding the car in the air can be seen in the back.
Revealing mistake: In the scene when the aliens first enter Valerie's house, Mac and Zeebo find the fish tank and eat one fish each. The shot turns to Valerie's stunned reaction then back to the aliens, who are smiling widely, pleased with their stunt. If you look at Mac's teeth, you can see they are bright white up to his first molar, which is a give-away at his fake white fronts.