Audio/visual unsynchronized: When the boys are teasing Chopper at the fence, Vern can be heard saying "Come on Chopper, sick balls Chopper", but his mouth doesn't move and instead he is seen smiling and laughing.
Anachronisms: The Topps baseball card in Gordie's brother's room was not available until after the film was set.
Continuity: Teddy's hair changes in every shot after being dunked in the swamp. The strap to his bag disappears and reappears as well.
Continuity: During the train chase, the sky goes back and forth from cloudy to clear.
Revealing mistakes: When Gordie looks at the newspaper article at the beginning, the first paragraph of the article is about the stabbing, but the second column is clearly from another story.
Anachronisms: The water pump shown at the end of the movie is a Waterous. The style was not available until the 1980s.
Continuity: When Chris comforts Teddy after Milo Presman insults him, Chris takes his hand off Teddy's shoulder in one shot, it then reappears on his shoulder in the next shot.
Continuity: In the swamp, Teddy's glasses go from being on his face, to being folded in his hand, to being back onto his face, and then we see him actually removing the glasses and folding them into his hand.
Continuity: Amount of blueberries and sauce on Lardass Davey Hogan's face before he vomits.
Anachronisms: 1980s cars visible in the background of the junkyard.
Anachronisms: Aluminum cans in the general store.
Crew or equipment visible: The camera tripod can be seen in Teddy's glasses when Teddy and Chris are arguing on the railroad tracks.
Boom mic visible: When Ace is playing pool with Billy, the boom mike bobs into view, near the light.
Boom mic visible: When Gordie goes into the store and the clerk talks to him, you can cleary see the boom mike bobbing into view and then being taken away.
Anachronisms: When Gordie visits the delicatessen for hamburger, the grocer pulls waxed paper from a box with a 1980s Crown Zellerbach logo on it.
Revealing mistakes: At the beginning, in the wide shot of Gordon Lachance's car, the man behind the wheel is an obvious stunt driver. So is the man driving Ace's car during the game of chicken in wide shots.
Incorrectly regarded as goofs: Gordie is not looking for his hat in his brother's room, he only reminisces about it there. It wasn't in that room, so it's not an error for him to be wearing it later without taking it from the room.
Incorrectly regarded as goofs: The narrator does not save his work before appearing to shut off his word processor, but that's okay, because in fact he only switches off the monitor, leaving the machine running and his work intact. Also, the shot of the narrator writing has him seated at his desk; when he turns off the word processor, he is standing, studying his work. It is reasonable to presume that a brief moment went by between the shots, and he could easily have saved the work then.
Crew or equipment visible: In the first train dodge scene, after Teddy and Chris make up, as Verne walks off back onto the train track you can see his wireless mike drop down his left leg and flop near his ankle.
Anachronisms: Ace's car has blue license plates, which were not available until the 1980s.
Anachronisms: The military jungle boots teddy is wearing were not available in 1959.
Crew or equipment visible: After Ace takes Gordie's cap, the reflection of half of a member of the crew can clearly be seen waving their arm in one of the store windows behind Chris and Gordie.
Continuity: When Gordie and Chris discuss Gordie's size, their positions change.
Continuity: The boys' clothes are dry right after they get out of the leech pond.
Continuity: When Ace and the others are playing chicken, the position of the logs off the truck change.
Continuity: When Lardass is confronted, and is half laying on the table, the man's hands change position.
Continuity: When Gordie and the others get back to town and are saying good-bye, the positions of Gordie and Chris change.
Continuity: When the boys are seen walking into the leech pond, they all fall in. We see Vern and Teddy go into the water, and when they come back up to surface, we can see Chris and Gordie on the surface already on the right side of the screen. However, in the very next shot, Gordie and Chris come to surface again.
Continuity: When the boys are at the leech pond Chris is seeing how deep the water is with a stick. The stick changes in size.
Miscellaneous: Leeches appear on Chris' back between shots when the boys are covered in them.
Audio/visual unsynchronized: When Vern climbs into the treehouse, his lips are clearly not matching what we hear.
Continuity: Teddy's left ear (which his father almost burned off) in the treehouse scene is very clearly burned. Throughout the movie, however, it varies in how it looks, in the train tracks scene it looks perfectly normal.
Anachronisms: When Gordie is in the delicatessen there is a bottle of Soft Soap in the background that was not available in 1959.
Continuity: When Ace is racing against his friends in the car, it clearly shows that he has blond hair, but when it shows the back view of his head, he has brown hair.
Continuity: When the boys are crossing the bridge, and Gordie is trying to help Vern to his feet there is a very brief cutaway showing that the oncoming train is only the engine and one car. The previous shot, and the later one once it passes, all show it to have several cars.
Continuity: When confronted by Ace's gang, Gordie shoots the pistol into the air, and then points it at Ace and pulls back the hammer. The pistol is a Colt 1911 and is an automatic, which means the hammer would have already been cocked after the first shot.
Factual errors: When the boys find Ray Brower dead in the woods, we see that he has sustained bad facial cuts and bruises, and that his face is still intact. However, if the body had been in the woods for several days like Gordie had said it was, and it was scorching hot and humid as well, the body would be so badly decomposed to the point that the face would not even be identifiable.
Continuity: When the boys are sitting by the fire cooking hamburgers and Vern's falls off his stick, it clearly falls apart. When he picks it back up with his stick, it is in one piece.
Audio/visual unsynchronized: When Vern is first coming into the tree house and is coming through the trap door he is clearly heard saying "You guys are never gonna believe this...”, but his mouth is saying the previous lines "Oh, man, oh, man".
Continuity: In the clubhouse at the beginning of the movie, Chris has a pack of cigarettes tucked into his sleeve. It disappears and reappears throughout the scene.
Errors in geography: Stephen King's original novella, "The Body", was actually set in Maine. The filmmakers, in error, set the film in Oregon instead because the city of Portland was mentioned, and Portland, Oregon is larger and better known than Portland, Maine.
Continuity: 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: When the boys get dunked in the swamp, Teddy takes his glasses off, but then while they're thrashing around in the water, both hands are clearly empty. Then, when they get out, he has his glasses in his hand again.
Revealing mistakes: In the train scene, River Phoenix's voice has suddenly changed and he looks older. This scene was obviously shot last, and he has started going through puberty. But in terms of movie time, he has gone through puberty in two days.
Continuity: All four guys are in the junk-yard and they are all about to toss their coins to see who goes to get the food. When Teddy throws his coin in the air he is wearing no dog tag necklace but when he catches the coin he is suddenly wearing the dog tag necklace.
Continuity: 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.
Anachronisms: 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 hash marks. Though the picture was set in 1959, center lines for passing zones on two-lane highways were painted white until 1971.
Factual errors: The narrator shuts off his computer monitor near the end of the movie, using a switch on the right-hand side of the monitor. He is using an IBM Personal Computer with the standard monochrome monitor, however, which has no power switch at all. Its power cord plugs into the computer, and it is powered on and off when the computer is powered on and off. The switch displayed on the side of the monitor is apparently a prop.
Factual errors: In the scene where Gordie goes into Denny's room looking for his canteen, there is a pennant of Michigan State University on the wall. Michigan State wasn't called Michigan State until 1964.
Revealing mistakes: In the "barforama" scene, the jets of vomit do not quite seem to come from out of the mouths of the actors.