Revealing mistake: When Weasel says, "How's your back, baby?" to Phyllis, she spits in his face, but Weasel closes his eyes before she spits.
Revealing mistake: When the killers first pull out Phyllis's severed arm to show Mari, the fingers are moving.
Revealing mistake: Mari breathes and moves when her parents find her body (the original intention was that she should still be alive at this point and would identify her attackers before dying).
Revealing mistake: When Mari asks if the guy has any girl friends, when Mari leans back there are Black dots on her face from a dirty camera lense.
Revealing mistake: When Krug hits Mari's friend after she bit him, you can see that he doesn't hit her. Her hair moves, but that's from the air from his hand.
Answer: She leaves him to bleed to death, which, without prompt medical attention, he surely will.