Continuity mistake: While Bart is being beaten up by Nelson and Jimbo, Nelson is on the right side and Jimbo is on the left side. In the close up shot, you can see from their arms that Nelson and Jimbo have switched sides.
The Simpsons (1989)
1 continuity mistake in The PTA Disbands

The Simpsons Christmas Special: Simpsons Roasting on an Open Fire - S1-E1
Continuity mistake: Lewis changes from black to yellow when Milhouse dares Bart to pull Santa's beard off. (00:14:10)
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: The Simpsons holds the record for most guest stars; it is also the only non-variety show to have had appearances from three former Beatles (Paul, George and Ringo).
Tree House of Horror V - S6-E6
Question: Homer travels back in time and causes changes by what he does in the past, like stepping on a bug. I once saw a movie with the same basic plot: some people travel back in time and are told to be careful not to disturb anything, but when they return to their time everything has changed. In the end they discover it was because they stepped on a butterfly. Does anyone know the name of this movie?





Answer: I'm not sure if this is the one you're thinking of, but an episode of "Ray Bradbury Theatre," called "A Sound of Thunder," dealt with a similar matter: a group of hunters travel back in time to hunt dinosaurs, only to find things have changed when they get back because someone stepped on a butterfly.
Xofer