Revealing mistake: After Amber and Jonesy are killed, the blood starts dripping on the son's face. Since when is blood black in color? This is a thick and syrupy-looking black liquid.
Revealing mistake: When Jake is being tied up, he's holding his hands up to make it easier for the cannibal to tie up. Also when they drag him out of view, he's holding his head up so it doesn't drag the ground, although he's supposed to be unconscious during all this.
Revealing mistake: When the hillbillies are dragging away Kimberly's body, it bounces along the ground like rubber.
Revealing mistake: Notice the guy who's hanging upside down. His intestines are hanging out of his body and they aren't even bloody. Neither are the other organs that have been cut out.
Revealing mistake: When Dale is shot with the arrow, the feather side is lower than the tip side.
Revealing mistake: After M gets his head cut off, you can see him breathing.
Revealing mistake: When Dale takes the necklace off Mara, you can see her breathing when she's supposed to be dead.
Answer: Possibly one of the girl's parents, hiding their little girl in the safe before being attacked, captured and killed by the Mutant family.
musicman