Occasionally, Nightmare Bonnie or Nightmare Chica can jumpscare the player even after the clock hits 6 AM if their attack animation was triggered at the exact same millisecond as the night's end.

A bug once allowed players to unlock the hardest mode instantly by pressing "2" and "0" at the same time in the menu.

In the very first release, pressing the "=" key allowed players to instantly skip a night. This was removed in a hotfix just 15 minutes later.

Players have reported that audio can occasionally cut out during the 8-bit minigames between nights. This is widely considered an oversight in the game's coding that was never fully patched. Gameplay & AI Oddities

Early versions of the game contained a few oversight "bugs" that were quickly patched out:

By manipulating game files (changing the save data to indicate "night n"), players can access a hidden "Night 9". Much like the glitches in FNaF 1 and 2, this night typically features no animatronic activity, allowing for a peaceful exploration of the environment.

This is the most notorious bug in the PC version. Because FNaF 4 essentially consists of a massive collection of high-resolution "GIFs," the game can hit a 2GB memory limit. This often triggers when Nightmare Foxy enters the closet; the screen may turn permanently black at certain doors or when checking the closet, as the game fails to load further textures.

If you unlock the "House Map" cheat, you’ll notice that Nightmare Freddy never appears on the radar. This is likely because his model only "spawns" into the room when he is performing a jumpscare, rather than moving through the halls like the others. Fixed Historical Bugs