I talked about this with a friend on Skype and both of us noticed it. The animatronic endoskeletons in Freddy's look a lot like the "Skelecog" characters from an old yet fairly known online video game known as "Toontown Online." These characters were variants of the normal "Cog" antagonists of the game, only without their suits. These "Cogs" were robotic businessmen, that could easily be considered animatronics of some sort, that hated fun and attacked the fictional town in the game because of it.
I'm bringing this up because it makes me wonder. Could these Skelecog characters have been a possible inspiration for the animatronic endoskeletons in Five Nights At Freddy's?