It's a Mad, Mad, Mad, Mad Marge - S11-E21
Factual error: When Homer changes Marge's oil, when he lies on the skateboard, there are no trucks (axle mounts on a skateboard) on it as there should be.

It's a Mad, Mad, Mad, Mad Marge - S11-E21
Factual error: When Homer changes Marge's oil, when he lies on the skateboard, there are no trucks (axle mounts on a skateboard) on it as there should be.
Continuity mistake: When Homer's Vegas wife shows him the video in front of Marge, it shows Homer kissing Ned. This didn't happen when she showed it in the Vegas episode.
Skinner's Sense of Snow - S12-E8
Nelson: Hey, look how much Skinner makes: $25,000 a year.
Bart: Let's see, he's 40 years old times 25 grand. Whoa, he's a millionaire.
Skinner: I wasn't a principal when I was one.
Nelson: Plus, in the summer, he paints houses.
Milhouse: He's a billionaire.
Skinner: If I were a billionaire, why would I be living with my mother? [All the kids laugh at him.] They're just not responding to logic anymore.

Trivia: Maggie scans as $847.63 in the supermarket at the beginning (not NRA4EVER, as Troy Maclure asserts in 3F31 "The Simpsons 138th Episode Spectacular), the price it costs to feed and care for the average American baby every month.
Who Shot Mr. Burns? (2) - S7-E1
Question: Chief Wiggum says that Space Invaders was an addictive video game, and Groundskeeper Willie says, "Video game?" I don't understand why he is so shocked. Could someone help please?
Answer: The joke is that Willie was so addicted to Space Invaders that he believed it was reality: every time he played, he was actually defending the Earth from dangerous aliens. It's a surprise to him that it was actually a game.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.