Continuity mistake: In the first shot of the scene where Gordie has a flashback of his family at the table, we see two pieces of corn near his plate. In the next shot of Gordie's plate, the pieces of corn are gone.
Continuity mistake: The blood on Gordie's hand change from shot to shot when he finds the leech downstairs, from being over most of his three middle fingers, to the ends of his index and middle, then to being all over again.
Continuity mistake: In between shots of Lardass as Gordie says "By the time he was on his fifth pie, Lardass pretended that he wasn't eating pies.", the crust on Lardass' forehead disappears.
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.
Continuity mistake: During the mailbox baseball scene, Ace is shown with a cigarette in his mouth. Then after he strikes out and says "ah shit, I'm out", the cigarette is gone.
Continuity mistake: In the leech scene when the boys get out of the water, Chris takes off his shirt and there are no leeches on his back. But when Chris says "Gordie there are some on your back man. Are there any on mine." he has about 4 or 5 leeches on his back.
Continuity mistake: About half way through their journey the boys clothes are very dirty, then they become spotless.
Continuity mistake: When the four boys first come to the railroad, Vern shows them his comb. He is holding it upwards, then lowers it a little. Then when Gordie says "Lotta thinking Vern, thanks," his arm is straight down next to his side.
Continuity mistake: After Teddy tries to dodge the train, the boys head back in the opposite direction they were walking. Not a question of camera angles. They're walking towards the oncoming train. After the train passes, they resume walking in the same direction it passed.
Continuity mistake: The author in the beginning is supposed to be Gordy grown up, but the grown up Gordy has blue eyes and light hair color and Gordy as a kid had brown hair and brown eyes.
Continuity mistake: At the story told by Gordie about the kid eating pies, at the last pie his face cleans up a little bit between shots.
Continuity mistake: When the boys are continue their journey the second day they are by each other eating blueberries but when it cuts Gordy and Chris are in front of Teddy and Vern while the others are both holding a string.
Continuity mistake: In the beginning scene, the newspaper clipping under the headline shows the first sentence to be about Chris' death from a stabbing, but the next line starts mid sentence about a completely different subject and the second column under the headline talks about taxes, mentioning nothing about the death.
Continuity mistake: All throughout the movie, the angle of the sun and shadows change within scenes. Especially in the scene when the boys are near the train bridge talking. As the camera shots switch, the shadows change angles.
Continuity mistake: Near the start of the movie, in the tree house scene, Chris has a cigarette packet rolled up in the left sleeve of his T-shirt, the cigarette packet is seen to disappear and reappear several times during this scene.
Continuity mistake: When the boys are roasting marshmallows, Verns falls off the stick in two pieces. When he picks it back up with the stick, it's whole again.
Continuity mistake: In the scene where all the boys are at the junkyard tossing their coins.Watch Chris reach Gordy back his coin, then the next shot Chris hands him the coin again.
Continuity mistake: Watch carefully in the scene where the four boys are running for their lives over the railway bridge. Chris and Teddy are in front, and Vern and Gordie are behind. In one shot we see just Vern and Gordie's feet, and quite a lot of the track behind them. You can see that there is no train behind them. In the very next shot, the train is about two metres behind them.
Answer: No, it wasn't that big of a train. He didn't even attempt to get off the throttle. That's all it would have taken for the boys to make it fairly easy. It was a straight-away track, no chance of it derailing by hitting the brakes. Like the man said above, if trains derailed that easily, we wouldn't be using them.