When the brown truck starts and a shot first shows the interior, it is the interior of the Mack that later attacks the couple on the highway. Another shot of the brown truck's interior shows it is clearly not the Mack, meaning that it was just repeated footage.
During the action that precedes the truck striking the Bible salesman and sending him flying, we see footage of him running away from the vehicle. When the two actually collide, it appears as though the Bible salesman is running into the truck, rather than the truck striking him from behind.
At the end of the movie Brad walks up and takes a ring from a dead woman's finger, leaning his gun up against the side of the car. The gun is tall enough to be seen through the rear driver-side window but in the next shot from the rear of the car the gun is gone.
When Duncan goes to get his son, his eyes are puffy from gasoline but there's no blood. Joe grabs his arms and we get a close-up shot of Duncan's face and there's blood all over his face. Then they cut back to longer shots and the blood disappears.
When the bridge starts going up on its own, it's fairly high. Then we cut to a shot of a truck in the middle and the level of the bridge has dropped considerably - it's almost level. Then we cut back to longs shots and the bridge is at its original higher elevation.
When Wanda is killed by the gun turret buggy, she fires off the M72 anti-tank launcher which hits and destroys a tractor trailer. This shouldn't have happened, since the M72 is a single shot weapon, and it had not been reloaded since Mr Hendershot fired it at the Bulldozer a few seconds previously.
At the end when the Dixie Boy survivors are leaving on the boat the person piloting the vessel has wavy hair, is wearing a blue shirt with a shoulder holster and was never in the film at any point. In the next shot the vessel is being piloted by Steve with his curly hair and Dixie Boy jumpsuit.
During the baseball diamond scene, when the boy riding the bicycle falls off in front of the scoreboard, his head is toward the scoreboard and the bicycle, tangled in his feet, is behind him. When the steam roller busts through the scoreboard, it should have run over his head first, and then his feet and the bike. Instead, it runs over his bike and feet first, and then his head.
In the scene where Curt and Connie are attempting to get into the truck stop, the beer truck is ramming their car after they are freed from it. The driver of the beer truck is visible for a few seconds.
The gun mounted on top of the motorized turret can not be controlled by the turret as shown when the turret comes alive. The gun is a separate item mounted on top of the turret, not part of the turret's mechanical system.
A caption at the start gives the time, to the exact second, of the passage of the Earth through the extraordinarily diffuse tail of a comet. Such precision cannot be achieved, due to the impossibility of defining the start & end of the transit.
When the Coach walks up to the soda machine the kids wait behind him in a group. In the background you can see a person standing in the field. It appears that this person is not supposed to be in the movie.
Signs visible throughout the movie list the price of diesel fuel at the Dixie Boy as $1.08 per gallon. Yet whenever the pumps are being used and the sale amount and gallons pumped are shown, the numbers work out to much less than $1 per gallon, actually just a miniscule amount over 56 cents per gallon.
When Bill gets called into Mr. Hendershot's office to discuss his time card the clock behind Bill says 10:06 (and approx 10 seconds). The clock is broken and reads the same time the entire scene including the second hand.