Revealing mistake: When Lardass pukes on the guy to the left of him, he moves his head prematurely, and you can see that the vomit is coming out of a jet (hose) positioned behind his head. (00:46:30)
Revealing mistake: Not to say Lardass was thin, but it is very clear that his shirt is stuffed up with some kind of padding to make him appear very obese, when he is announced for the pie eating contest.
Revealing mistake: In the car race scene with Ace and his gang you can see that it is not Ace driving when the car runs over the wood in the road.
Revealing mistake: During the pie eating scene when the projectile stream of blueberries starts, the alignment is off for most of them, as it appears to come out of their noses and chins as well. The pie eating contestant next to the radio personality has their stream fall in an arc until it looks like it's coming from beneath their chin directly downward.
Revealing mistake: When Lardass is getting ready before he comes up onstage, listen closely when he drops the egg into his mouth, and you'll realise that it isn't going into his mouth, it is landing on the ground. You can tell, because you can hear it hit the ground.
Revealing mistake: When Ace runs the truck driver off the road, it's obvious that Ace Billy and Charlie are stunt doubles, because of the hair and age.
Revealing mistake: When Davey cracks the egg, you can tell he doesn't crack it into his mouth. It slides down his cheek and hits the ground. You can actually hear this happen.