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.
Factual error: When the two drivers of the teenage gang are playing "Chicken" on a straight section of a two-lane highway, the center lines of the road consist of yellow hashmarks. Though the picture was set in 1959, center lines for passing zones on two-lane highways were painted white until 1971.
Revealing mistake: When Lardass pukes on the guy to the left of him, he moves his head prematurely, and you can clearly see that the puke is coming out of a jet positioned behind his head. (00:46:30)
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 amount of blueberries and sauce on Lardass Davey Hogan, before he vomits, changes from shot to shot. (00:46:10)