Revealing mistake: When the announcer says that the Falcons win, he says "Who would've thunk it" Homer says "My daughter, that's who". When he is saying this, Lisa's arm disappears twice. (00:10:05)
Revealing mistake: When Homer leaves the bar after the Superbowl, as he goes through the door, the background is missing. It's just a brown background. (00:20:00)
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.