Stan and Kyle switch places in the blink of an eye as Stan address the mob after his house is bombed.
Mrs. McCormick's T-shirt switches from "I'm with stupid" to "God Bless" at the very end.
Kevin, Kenny's brother, walks up with him and the other boys at the start of the show, then disappears when Grandpa enters. Then he and Shelley show up on Kenny's left at Cirque du Cheville.
A third leg appears on Grandma just before Kenny reaches the finale.
When a man tosses a fish stick to the girls, it actually falls to the ground outside the chain-link closure, but one of the girls manages to catch it in her mouth and eat it.