Here's some lovely Fridge Horror for you folks. During the ending scene Mike, Dave and Debbie get pelted with goop from the exploded tent. Seems like a cute ending joke, until you realize that it's pie. The same pie shown in the movie to be highly acidic and capable of reducing a human to bone.
The scene where the Klowns capture the farmer's dog. The fact that you never see what happens to it makes it worse than the other deaths.
If you look closely at the first time you see the cotton candy room, there is a cocoon next to the farmer that's smaller than all the others. Word of God in the director's commentary confirms that is the dog...
The line "Don't worry, Dave. All we wanna do is kill you." soon after Mooney is killed.
The scene where the Klown tries to lure the little girl out of Burger Fool. This is the only time in the movie when a child is even shown, let alone in danger. The background soundtrack fades out, replaced by a very creepy chorus. It's effective, and not played for laughs at all.