I think it got the ol' pg rating even though it does have the scene of the man tearing his face apart because well.........it was crappy.......it was stop motion claymation and looked nothing like a human or blood.......I guess the MPAA saw that scene, laughed at it, then decided that no child could possibly be anything other than amused by that scene..........
The MPAA wasn't very estrict back then, Indiana Jones and the Temple of Doom was PG even though you see a man tear another man's heart out from his chest. Then you see that man going down into some sort of lava pool and he starts burning. Gremlins was PG as well and they show how the Gremlins toss an old lady out from a window, and you see a Gremlin getting killed in a microwave, another one in a blender and another one decapitated and his head starts burning.