When Beverly goes to her childhood home, the closeup of the doorbell says "Marsh." However, in the next longer shot, it says "MARSH." Also, the red and white wire going into the bottom of the doorbell in the closeup become two white wires in the longer shot, and the position of all four wires, two on top and two on the bottom, change.
When Beverly flees from the Marsh house, a truck approaches her and the horn honks. However, the shots of the driver show he has both hands rock-solid on the wheel, which means he can't honk the horn.
When Mike opens the refrigerator and the balloons pour out, there are four cans of pop in the door. There are three clumped together toward the refrigerator and one separate on the outside. When the camera cuts to a shot of Stan's head inside the refrigerator, all four cans are clumped together.
When the wind blows through the library, it blows off most of the books on the top shelf. However, in the next shot they are back in place as the ones on the lower shelves blow off.
When Ben goes to Beverly's room to get her shawl, the cloth she picks up is white with blue flowers. However, when Beverly comes in and he gives it to her, it is purple and pink striped.
In the sewers, as the paper boat first approaches and then departs from the friends, the shadow of the steadicam following it can be seen on the brick wall to the right.
When Audra falls out of the web in It's lair, she is covered in webbing. However, when Bill sets her down all of the webbing instantly disappears.
In the movie the words "Beep beep, Richie" are often used. In the novel it is explained that this phrase is meant to get Richie to shut up.
Pennywise: Excuse me, sir? Do you have Prince Albert in a can? You do? Well, you'd better let the poor guy out. Wah-hah, wah-hah, wah-hah!
Eddie: I'm okay. I think I remember who Pennywise was now. Big white guy, red nose, about 75 feet tall, mouth full of razor-sharp teeth.
Ben: How many times have you been to the altar, Richie?
Richie: Oh, four or five. Who the hell keeps count? Women all want the same thing. No offense, Bev.
Beverly: None taken, creep. Welcome to the 4th century.
Richie: It's greet to be back in Derry, breathing in that old "Derry air."
Stan/Pennywise: I finally made it, guys. I'm in the deadlights now. And you know what? It's true what they say. We all float down here. And you will, too. In fact, they all float! They all float!
Belch/Pennywise: I need you, Henry. We all--we all need you.
Henry: They can't hurt you.
Belch/Pennywise: We didn't think they could hurt us back then, either, but they did, didn't they? Bested you all summer.
Henry: Don't you talk about that.
Belch/Pennywise: I can take care of them if they only half-believe. But you, you're alive, Henry. You can get them no matter if they believe, half-believe, or don't believe at all.
Bill: Anybody asks, the party got out of hand, dancing on the table, you took a fall.
Mike: Anyone who's seen me dance will buy that.
Bill: I just saw something, and I have no idea if it was real. If any of you would have seen it or not. I can't go. Because if I do, I'm going to live with this until I go insane. Until I can't tell the difference between my life and my bad dreams. For years I've been getting paid to scare people, but I'm the one who's been scared all my life. I don't want to be scared anymore. I'm going back in. This time I'm going to kill It.
Bill: These are for him, and for Stan.
Eddie: Lucky Seven.
Ben: We're all here now.
Richie: Oh come on, guys, what the hell are you going to do now? Sing Kumbaya? Wake up, take a breath. Do you smell that? That's death. It's not for Mike, it's not for Stan, it's not for Henry Bower. It's for us. It's in the air. Losers fight It, Losers die. And you know that, don't you, Captain?
Bill: You don't have to go down there, Richie.
Richie: Right. I didn't have to get on a plane in L.A., I didn't have to go to the dinner, I sure as hell didn't have to come out here. And now I don't have to go in. I still say we should have brought a machine gun.
Eddie: I believe in Santa Claus. I believe in the Easter Bunny. I believe in the Tooth Fairy. But I don't believe in you. This is battery acid. Now you disappear!
Bill: (trying to read a paper) He th-th-thrusts hi-his fists...
Ben: "He thrusts his fists against the posts and still insists he sees the ghosts." That's all it says, over and over.
Bill: My m-m-m-om g-gave me that to to to... sttttt! to help with my st-st-st-stutter!
Richie: No offense, pal, it ain't workin'. (blows him a kiss)
Richie: (to a dying Eddie) Don't talk. You're gonna be fine, Spaghetti-Man.
Eddie: Richie, please. For the last time, don't call me that. You know how I... (dies)
Pennywise: Beep Beep,Richie! They all float down here! When you're down here with us, you'll float too!
Eddie: I have to tell you guys something before we go in there.
Eddie: Yeah. I've been lying.
Ben: About what.
Eddie: When I said I was seeing someone. Well, I'm not. In fact, I haven't ever... I mean, I've never even been with anyone.
Richie: Eddie, Eddie, what are you saying? You're a virgin?
Richie: Well, I can't help you with that, pal, but thanks for sharing.
Bill: Audra, this bike saved little Stan's life once. Mine, too. We were going so fast, I think I beat the devil. I don't know if I can go that fast again. Hold on.
Music: The Way You Do the Things You Do (The Temptations), It's All Right (Curtis Mayfield)