Factual error: Asystole (the lack of cardiac activity, also known as the 'flatline') is not treated with defibrillation (electric shocks) but with alternating doses of the drugs epinephrine and atropine.
Factual error: Throughout the entire film Burt holds all of his rifles' butts underneath his armpit, rather than against his shoulder. A trained "survivalist" such as him would surely know better. Holding the "elephant gun" in such a way would most likely break his arm, wrist and hand when it fired. (00:58:20)
Factual error: When the Security Guard in the pump room gets bitten on the nose, he starts shooting with his revolver (a SIX shooter). Count the bangs. He manages to fire SEVEN times. (00:39:45)
Factual error: During the scene where Peyton is hanging from the helicopter, Durant is firing at him with a grenade-launcher. He hits several cars, most of which end up in flaming wrecks. Despite this, traffic continues as normal... If you saw cars around you exploding, would you casually continue on, oblivious? This error is especially visible with the truck driver, whom reacts to Peyton landing on top of his truck, but seems oblivious to the chaos behind him.
Factual error: The spider being fried by the fuse box simply can't happen. Fuses are insulated for that very reason.
Factual error: Near the end of the movie, Jacob takes a cab to go back to Brooklyn, supposedly from another part of New York. However, in the next shot, we see that at the beginning of the ride, they are already in Brooklyn (on Division Ave, for those who know Brooklyn).
Factual error: The blonde cop is thrown into a hardware store. She then grabs a brand new, shiny chainsaw that was sitting on a cardboard stand-up display. Then, of course, she goes to attack the maniac cop with the weapon. A new chainsaw that was on display wouldn't have gas in it.
Factual error: Most of the time when Eddie uses his inhaler, he uses it wrong or doesn't even spray it in his mouth.
Factual error: Barbara has blood drip on her in the first scene when she enters the house. Later that night, Ben starts upstairs but Barbara stops him and points to the blood dripping from the ceiling... the blood would have dried and clotted in the time that it first dripped on Barbara and the time that Ben Starts upstairs.
Factual error: The Chicago Fire Dept fire truck is red but the real Chicago Fire Department colors are black over red. (00:59:20)