Factual error: A doctor is seen using a syringe to inoculate the individual with the disease. It is clear that the containment gloves and sleeves he is using are not proper as you can see his skin between the gloves and the sleeve. If this were a real containment unit his entire skin would be covered. (00:31:00)
Visible crew/equipment: When Paul pokes the dead body with a stick, you can see a diver's arm turning the corpse over.
Other mistake: The Blazer was only hit twice by the baseball bat, once on the right front fender, and once on the grille, but it sustained a massive amount of damage. Also, when the infected guy was inside, throwing up blood, you could see that the windshield was cracked in several spots, but it was never hit.
Continuity mistake: When Marcy leaves Karen's side to confront Jeff, in the first shot Karen's blanket is tucked under her legs. But in the next shot, her blanket is lying loose upon her mattress. Also, leaves that are bunched up at the side of the mattress disappear between shots. (01:00:50)
Answer: They don't know about it. The only resident in town to contract the disease was the hermit. The sheriff even remarks to Deputy Winston on his radio that the kids at the cabin were going on a killing spree and that they had some kind of skin disease, indicating the disease was heretofore unknown to them. It's possible that the hermit's dog was the carrier.
Phaneron ★