Continuity mistake: When the 7 kids throw stones at Henry Bowers he gets hit, falls down and starts to bleed on his forehead. When he later gets up and walks away there is no bleeding on his forehead.
Continuity mistake: When they are in the library after they found out Stan committed suicide, it shows Beverly stand up but when it cuts back to her she is sitting down and stands up.
Continuity mistake: When the clown is causing the library to be the target of a windy rainstorm, the books are being pulled off the shelves row by row. They cut back to the shelf where the books have already been pulled off, and yet there are still many on there!
Continuity mistake: In the part where the 7 kids are looking at Mike's photo book, Pennywise turns the page to the picture that comes to life. When the page is first flipped, you can see that on that page, there are a few pictures on that page. But, when Stan throws the book on the ground, that picture is the only one on that page.
Continuity mistake: When Ben is running from the trio, he goes into the Barrens and spots a drainpipe to hide in. The pipe has a smooth-surface and has water running from it. When it shows Ben hiding in it, the pipe is rifled and there's no water coming out of it. It's not even wet on the inside.
Continuity mistake: The blood splatter in the restroom scene splatters Beverly in the face with a noticeable amount of blood. In the next scene where Beverly's dad is in the restroom, the quantity of blood has decreased.
Continuity mistake: When grown up Beverly is throwing stuff at her boyfriend, she picks up a bottle of rocks or something like that and throws it at her boyfriend but when it gets to him, it has magically changed into a shampoo bottle. (00:35:15)
Continuity mistake: When the bullies grab Richie in the cafeteria and pull him away, his plate has peas in the front and mashed potatoes on the right side. Then when Henry takes some potatoes and smears them on Richie's glasses, the potatoes are at the front of his plate, and the peas are at the back.
Continuity mistake: Young Bill has a dimple in his chin that old Bill doesn't have.
Continuity mistake: At the beginning when the blonde girl is in front of the clown, she has a tricycle beside her which disappears and reappears between shots.
Continuity mistake: Before Georgie is taken by the clown at the Seward the grid is not seen because of the water, but in the next shot the water is gone.
Continuity mistake: In England while Bill is about to take dinner his wife puts some blue papers on the table. In the next shot they move.
Continuity mistake: Using the slingshot, when Bev is about to shoot the cans and bottles, there are 2 white bottles, 2 black bottles, and 3 brown cans. After she shoots the bottles, somehow a third white bottle appears to be shot after the first two were already gone.
Continuity mistake: Richie is wearing a green brown and white striped shirt when we first see him in the school. But moments later he's wearing a solid mint green shirt.
Continuity mistake: Pay attention during Bill and Audra's bike ride. She starts out wearing hot pink shoes yet when going down one street they've suddenly turned black or brown. A shot later they're back to hot pink.
Chosen answer: It's their way of telling Richie to be quiet. To get him to stop talking.