The spare tire on the back of Jenny's white Jeep disappears and reappears numerous times while driving into Snowfield.
When Flyte turns off the power in the "tank" so that they won't be overheard through the electronics, there is still one computer screen on and functioning.
Everyone goes into the lab and it begins to snow. Jennifer, Lisa, Bryce, and Flyte are the only people left in town. Yet, when Flyte leaves the lab later, there are footprints and tracks in the snow.
When Lisa is in the bathroom, she drops a cigarette into the sink. The position of the cigarette changes in the next shot. Then, in the following overhead shot, there are two cigarettes in the sink instead of one, and again in a different position.
The band-aid on Sheriff Hammond's neck changes repeatedly throughout the movie without any way it could have been changed.
Jenny says that Snowfield has 400 residents in the winter when it's slow, but Snowfield is a ski town, so the busy season would be in the winter, not the summer.
The doctor remarks that the human brain weighs about 6 or 7 pounds. Actually, it is around 3-1/4.
General Copperfield is wearing a single star on his patrol cap, but is wearing two on each shoulder of his field jacket. Rank insignia on the patrol cap should match the rest of the uniform.
When the body of Deputy Henderson (actor Larry Odien) is found, several empty shell cases are found around his body showing that he had fired at (and presumably hit) whoever or whatever is involved in the missing/killing of the townspeople. The empty shell cases shown are of a "bottle-necked" design. While the Beretta 92 series pistol that the deputy carried is available in several calibers none are of a bottle-neck design. While this type of ammunition IS available in some handguns, it's use is far more common in long-guns such as carbines and rifles.
The spent 9mm shell casings on the floor of the police station are from blank rounds.
The movie takes place in the fictional town of "Snowfield," Colorado, but several signs visible on the street (i.e. at 8:50) are marked "Georgetown," the name of the real-life town where the movie was filmed.
In the bakery, when the timer goes off, it makes a bell sound. The timer is an electronic timer that makes a beeping noise when it runs out.
In the middle of the movie in one of the rooms at the hotel where they just discovered a dead body (which disappears).