> It's kinda cool how there's an It reference when one of the actors appeared in It.

I know right! Lol!

okay I added in the Headless Horseman next one on the list is the skull-headed spiders.

When Stine mentions that his books have only gotten loose once before, and then subsequently recants it to say that it's happened a number of times, I took it to be an indirect reference to the two Goosebumps movie tie-in games, which did have his books getting loose before and (maybe, since Night of Scares chronology is unclear) after the events of the first film. 

Here's an interesting one I picked up: In a scene set in Fred's Pharmacy, a Trick or Treat for Unicef box can be seen on the counter. Trick or Treat for Unicef 2018 was sponsored by Goosebumps.