Gulf Wax in the opening sequence
As Bill makes Georgie’s boat (that boat), he asks him to get some paraffin wax to make it waterproof. The brand, Gulf Wax, is the same brand used in the book.
Bill’s bike, “Silver”
There’s a reason that Bill’s bike “Silver” is slyly focused upon throughout the movie. In the book, it’s Bill’s only release from the darkness in his world after (somewhat spoiler) Georgie’s disappearance.
Pennywise referencing Richie’s fear
In the book, Pennywise adopts various guises to terrorize the kids. In the films, we see a few. However, Richie’s really isn’t alluded to unless you notice when they’re in that creepy AF house and Pennywise goes to attack, his hand briefly turns into a werewolf claw: Richie’s fear in the book.
Removal of a questionable scene
Sure, things were different back in both the ’80s and ’50s when the first half of the book was set, but it was a wise choice to leave out the Losers’ Club orgy at the end…
Derry’s pretty disastrous past
In the novel, the fictional town of Derry, Maine’s past is well delved into. Of course, movies don’t have the luxury of time, so a lot things, like the Bradley Gang shootout (a mural on the wall next to the butchers) and the fire at the Black Spot, a club for Derry’s black population, is reference by the kids.
Jackson Street and Witcham Street
Here’s another subtle nod to the books. While a street sign may seem fairly average, these two streets are particularly noteworthy in the book, as Stephen King builds his description of Derry perfectly, right down to the street on which this iconic scene takes place. It’s referenced multiple times in the original book as a pretty cursed place — as if Derry isn’t already.
The innocently ominous final scene
As the characters hold hands in a circle, vowing to return if It ever does, they leave one by one. Big deal, right? Well, that plays a big part in the books, and without giving too much away, all we’ll say is if it were you, you’d want to be one of the last to leave. Presumably, this should be something we’ll see in Chapter 2.