Continuity mistake: When Gordie shoots the garbage cans and runs off, he's still running when they get around the corner and he's not holding the gun anymore. He wouldn't have dropped it because it's in later scenes, and he didn't have enough time to put it in his backpack or give it to Chris because they were trying to get far away from the back of the diner.
Continuity mistake: In the opening scene there is a shot of a person sitting behind the wheel of the jeep. This is supposed to be Richard Dreyfuss, however it is not. The hairline is different both over the forehead and over the ear.In the very next shot you actually see Dreyfuss sitting behind the wheel of the vehicle and you can see his hairlines are much different.His hairline is receeding and there is no hair over his ears where in the opening scene the person has hair over his ear and on his forehead.
Continuity mistake: The train on the bridge is producing black smoke from its funnel, but in one shot it is producing white smoke.
Continuity mistake: The amount of blueberries and sauce on Lardass Davey Hogan, before he vomits, changes from shot to shot. (00:46:10)
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.
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.