Character mistake: Theo applies a tourniquet to Lydia's torso in order to stop her from bleeding, he is later congratulated by Melissa who is a nurse. Tourniquets are not to be used for heads or torsos, only limbs.
Factual error: The operator that receives the 911 call only sends the police, when in actuality if a caller is silent during their call, the operator has to send out all emergency services.
Character mistake: Tracy supposedly rips Lydia's tongue out to stop her from screaming. The only problem is that the tongue is not needed to produce a scream.