A mistake in the saw movie Series?

I think i may have found a mistake in the saw movies. It's starts in saw 4, at the ending, when the black guy sees hoffman- the cop, is the new jigsaw, it then flashes back to the angel ribcage trap from saw 3, it recalls one of the cops saying amanda couldnt get her up thier by herself, then hoffman says" but jhon(jigsaw).." and the cop goes" he's brain not brawn(strong)", but ammanda must have made that trap becuase it was an un-beatable one, becuase at the end of saw 3 at ammandas death, jigsaw said he was tesing her, and he says "your test subjects were mearly victems," when he says it it flashes to the ribcage trap meaning the girl cop who was in the trap, was treated un-fair, and ammana made it,but what i dont get is at the end of 4 it doesnt say who helped ammanda, as hoffman couldnt help her as ammanda never knew about hoffman being jigsaws apprentaince. so whats up with that? and what does the note say that hoffman gave to ammanda?