Nightmare On Elm Street 5 Sign
This easter egg can be seen in all versions of the movie.
Following the scene after Beverly and her father have an altercation in the bathroom at her home and Bill finds a message from Pennywise scribbled on the walls, viewers are shown the outside of the local movie theater. If you look quickly you’ll notice the movie currently showing is Wes Craven’s movie, “Nightmare On Elm Street 5”.
In an interview with Nerdist, Andy Muschietti, director of IT stated that he briefly considered including Freddy Krueger as a character that Pennywise would morph into, but decided against it. Though it is worth noting that the A Nightmare On Elm Street franchise is owned by New Line Cinema as well, which likely played a part in it’s mention.