Plot hole: It is shown that Marge first met Luann van Houton when she was ten. But in "Homer Defined", Marge said that she first met Luann in an emergency room when Bart and Milhouse drank paint.
Plot hole: A little ways into the episode, when Milhouse kisses Homer, he says that was the first kiss in his whole life. However, we see him kissing Samantha Stanky in the episode "Bart's Friend Falls in Love," in Season Three.
Continuity mistake: When Marge is saying she would never have married Homer if she had known it was him in the camp, she is on the couch. But in the next shot, Marge is standing up and the cat and dog are on the couch.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.