Continuity mistake: When Gordy returns to the junkyard after getting the food he sees his friends running away. The junkman yells at him and Gordy starts running away towards the fence. In the background he passes the same junk vehicles multiple times. (00:26:15)
Continuity mistake: When Gordie jumps over the fence away from Chopper and they all realise he's not fierce, the boys start to tease him. While Teddy's saying "Bite my ass, Choppy" the dog bites through the fence and Teddy pulls away, and then in the next shot he pulls away again and jumps differently.
Factual error: When Gordy goes to get supplies at the store, as he is standing there the clerk is talking about Denny, and in the background on the shelf there is a bottle of Soft Scrub. It's supposed to be the 1960s, but Soft Scrub was not around until the early 80s. (00:25:00)
Continuity mistake: When Chris gives Gordie the loaded gun and it goes off behind the diner, they run away around the corner and Gordie get really mad Chris tricked him. Chris stops Gordie in front of a pale beige wall, and then when Chris tells him he didn't know it was loaded, they are in front of a glass window.
Continuity mistake: Gordie's hair constantly changes throughout the film from floppy to gelled, i.e. in the scene on the trestle over the water he yells, "Train!" and his hair appears to be quite dry, without a parting. In the next short scene around the campfire, it looks perfectly combed and gelled. He can not have borrowed Vern's comb, since Vern lost it on the train bridge.
Revealing mistake: Not to say Lardass was thin, but it is very clear that his shirt is stuffed up with some kind of padding to make him appear very obese, when he is announced for the pie eating contest.
Continuity mistake: At the end of the first shot of Lardass drinking castor oil, the bottle is nearly full, but at the start of the next shot, the bottle is nearly empty. Because of the people talking in the background, they couldn't have cut forward to the part where he is finishing.
Revealing mistake: In the car race scene with Ace and his gang you can see that it is not Ace driving when the car runs over the wood in the road.