in the shop of rockclones, luigi's hat can be seen in the shelves, this refrences fnas 4's ending
all of nightmaric's lines in MM are refrences to him being scrapped, with one being a refrence to the easter egg in fnas 4 for turning off everyone
almost all games in the series do something that crashes the game if you turn off everyone, MM and fnas 3 are the only ones that dont do this, as salvage cant be turned off in fnas 3, and B.T just kills you instead of crashing the game in MM
half the community are simps for toy tails
one of toy tails' lines refrence rockclones, specifically the one where she talks about you not having a blaster
in MM, if a phantom attacks you at the same time as a character that isnt from fnas 3, the jumpscare sound will be of fnas 3 instead of whichever should play, this is a bug
the reason why clone mario and clone yoshi exist is because ian wasn't sure how to draw other sonic characters, and he wanted his fnas take to be diffrent than the rest
golden sonic was originally meant to be red/orange, but it was scrapped, it seems to be coming back in all-stars tho
fnas 5 was originally meant to go from 12 pm to 12 am, but after the nights were made somewhat long cuz of it, it was scrapped
fnas 3 has a secret easter egg with phantom bew where in one cam, one of the posters may change to his, if you keep staring at it, you'll die, as well as unlocking him in the extras
like in fnas 3, in fnas 2 there exists a secret of luigikid replacing a poster in one cam, and killing you if you keep staring at it
in MM recoded, if you type and hold M T X while looking at N. Mario, he'll change into M.X Mario, he's the only character with voice lines
despites being the creator of the clones and phone guy of fnas 5, tails is never a security guard, and as such plays a small role despites making the clones
in MM recoded, clone tails' jumpscare can be delayed by a second or 2 by looking away from him when he enters, since he only initiates it once he's in the center of the screen
each one of toy sonic's lines are refrences to memes (no not the toy sonic that is @GreenStarAKAToySonic2023's OC)
fnas 3 was the first game to increase the time it took to win to 8 am, as well as the first one that had any unique mechanics

this is pretty much everything, theres more but im too lazy to cover all of them XD