The City of New York vs. Homer Simpson - S9-E1
Factual error: The windows of the World Trade Center couldn't open and the Twin Towers weren't in front of each other as depicted in this episode. They were at an angle.
Bart Carny - S9-E12
Factual error: Sharks cannot just reverse backwards like that one did under the glass bottom boat. The only way sharks can go backwards is either swimming around in a circle or allowing the current to carry them.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.