Bill: He thr-thr-thr-thrusts his fi-fi-fists ag-ag-against the pos-posts and...
Ben: He thrusts his fists against the posts and still insists he sees the ghosts. That's all it says over and over.
Bill: Th-th-thats w-w-what m-m-my m-m-mom g-gave me t-to h-help with my st-st-stutter.
Richie: I hate to tell you buddy, it ain't working.
In the library scene when Richie sees Pennywise the clown, all the balloons filled with blood are popping on people who aren't supposed to be able to see them, but one lands on a lady and you can see her jump as the balloon pops.
When the adults walk into the library, you'll see some of Bill's books on display (Bill is described as the Stephen King character), and all of Bill's books (Whether it's the name, topic, or cover picture) are based in some way on Stephen King's books. For instance - The Glowing/The Shining.