Continuity mistake: When the boys are in the treehouse at the beginning, the coca cola bottle on the treehouse shelf constantly moves places between shots. The two sides of the bottle saying "coke" and "coca-cola" keep switching positions between shots also. (00:02:55 - 00:04:55)
Continuity mistake: 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. (00:22:15)
Continuity mistake: When the boys are at the junk yard and they nominate Gordy to get the food, when Gordy jumps up and starts joking with the boys, Vern and Chris start to fight. Then the shot changes and suddenly Teddy, who was off to the side, is in the middle of the pile. (00:23:35)
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: The amount of blueberries and sauce on Lardass Davey Hogan, before he vomits, changes from shot to shot. (00:46:10)
Continuity mistake: 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. (01:02:05)
Continuity mistake: When Gordie, Chris, Vern and Teddy fall into the water, Teddy and Vern go completely under, but Gordie and Chris are able to keep their heads above the water. In the next shot, all four of them emerge from under the water. (01:04:15)
Continuity mistake: When the boys are dunking each other in the swamp Gordie starts to wade away, when he passes the camera his hair is dry but when he reaches the bank it's wet again. (01:04:56)
Continuity mistake: In the beginning he mentions Teddy's left ear being burnt by his father on a stove. Notice how his ear goes from looking severely burnt, to not burnt at all, through the movie. Especially the water dunking scene.
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: In the tree-house scene near the beginning, the sleeve on Chris's t-shirt changes from being rolled up to rolled down. The most noticeable example of this is when they lift up the table to let Vern in and it cuts from a close-up to a wider shot.
Continuity mistake: Towards the end of the movie just after Gordie has scared off Ace and the gang, Gordie turns his head towards Chris when his friend repeats the "suck my fat one" insult. When the camera cuts, Gordie's suddenly facing forward again.
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: In the treehouse, Gordie has a hair dangling over his forehead. But at the end of this scene, when they decide whether or not to go get the body, Gordie says "Sure," and the hair over his forehead is gone and his hair is neat and combed.
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.
Continuity mistake: When the four are deciding whether to cross the swamp, Chris pulls off a nearby tree branch to test the deepness. First the branch is quite flimsy and has two ends like a "Y" shape, and then after Chris pokes it into the marsh it becomes thicker with no split end.
Continuity mistake: When the boys are up in the treehouse at the start of the movie, at one point Chris blows out some smoke into a cloud in front of him, but in the next shot it's completely disappeared.
Answer: A cello.