Factual error: In the final scene where the gas grill blows up, the arm that falls to the table in front of the mother is not from a teenager - it is nearly twice as large as the young man's arms (as previously seen in multiple scenes). Some people say it's a leg, but if that's so it's a bit odd having fingers on the right side of it... (01:25:11)
Factual error: When the surviving state trooper is searching the police database for Alex Browning the search results pop up in a new window although the box that says "Open in new window" is unchecked.
Factual error: When Timmy (the kid who gets crushed by the glass slab) is at the dentist, the tube on the water tank comes off and water spurts out. That tube is the water intake, so if it were to break of it would be sucking in air, it would not be spurting water out.
Factual error: In the scene with the defibrillator it shows on the trace that her heart rhythm is asystole. Defibrillators only work with shockable rhythms i.e. VF (ventricular fibrilation) or pulseless VT (ventricular tachycardia). Using one on an asystolic patient would have no effect at all.