1: The actor who plays William Afton also plays one of the killers in Scream and more surprisingly, Shaggy from Scooby Doo.

2: In the storage room where you see a demonstration of the springlocks, you also see the head of the doll on the cover of Five Nights at Freddy's Fazbear Frights: 1:35 AM who is extremely similar to Ella (novels) who is later revealed to be toddler Charlie.

3: In the torture room, my dad noticed a Fetch-looking animatronic. I don't want to watch the entire movie to look for that again.

4: The knife-wipe that William Afton does is a reference to Scream when the villains also do it. (Probably because the actor for Afton did it in Scream)