Continuity mistake: When Homer is being hypnotised, in some shots there are plates on the Simpsons table, in others there are not.
Continuity mistake: At the end of the episode, Homer puts a skull in a box on the coffee table. When Moe arrives to explain his theory, first the box disappears from the coffee table, then the entire table vanishes.
Continuity mistake: When Homer first finds the corpse, there is no belt on the trousers it is wearing. But in the shot where Homer starts to scream, there is a belt on the trousers.
Continuity mistake: When Marge throws the Burly paper in the water, they start growing and sucking up the water. But the things inside that rolls don't grow.
Continuity mistake: When Homer first lifts the corpse up, it is wearing glasses. But when it cuts to the shot of the corpses' face, the glasses have gone.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.