Revealing mistake: When Chevy Chase is dreaming that he is flying and coming in for a landing you can see the rod that is holding him up as he is squirming around while flying. (00:28:00)
Continuity mistake: While Chevy's car is being covered with radioactive foam from the truck in front of him, following shots alternately show the car with and without foam.
Visible crew/equipment: When Chevy Chase goes into the breakroom at work, shortly after he gets his powers, the model plane ashtray starts to fly around the room. At the bottom of the screen you can see the object used to hold it up.
Continuity mistake: When Dorita is pouring the "demon powder" around the bed, she makes straight lines to follow the bed. When Max snorts it, the line curves around the foot of the bed.
