Continuity: In the scene where the spiders are starting to attack the city, it shows the guy in the barber shop closing up. He shuts the blinds then his friend gets attacked by the spiders, then he goes back out in front and the blinds are still open.

Continuity: When the townsman flees the Diner and gets into his car to flee, the front car window is wound up. The next shot of his face clearly shows the window wound down yet his hands have been busy starting the car all the time.

Continuity: In the scene where the townspeople are fleeing to the mall there is a shot of the Deputy driving the car. You can see the top left hand corner of the windshield is covered in green goo, but when you see them parking the windscreen is completely clean.

Continuity: In the bedroom scene where the sheriff goes in to talk to her son, the movie "THEM" is playing on the TV set. It pans back and forth a couple of times throughout the scene from mother and son to the movie on the TV and the scenes from "THEM" are all out of sequence.

Other: Every person in the movie has exactly the same make and model of computer with exactly the same desktop configuration on it. The number, type and order of icons is the same, as is the plain blue background.

Continuity: When Chris' Aunt Gladys is searching for her missing dog (it went looking for strange noises inside a wall) her cigarette is burnt out. After a change of the camera angle, she smokes a fresh cigarette.

Continuity: When Scott Terra hitches a ride from David Arquette the shot from inside the truck shows that the passenger door is locked. Scott Terra has no problem opening it, though.

Factual error: The spiders shown in the movie have no adhesive pads like real spiders, but only sharp points on the tips of their legs. Given the mutation, this is possible, but without their gripping apparatus, they should not be able to climb up anything.

Audio problem: In the scene where all the towns residents take refuge in the Prosperity Mall, the mall's janitor/caretaker guy says something to the female sheriff with the camera facing him. In mid sentence the camera angle changes to behind the janitor but at an angle - you can hear him keep on talking but you can see that his jaw is perfectly still meaning that he can't possibly be talking.

Continuity: Wade is about to get into his car when he notices people driving up to the mall. He rotates ninety degrees between waving to the arrivals and the wide shot on the mall front, then the next shot shows him turning that way.

Audio problem: When the mayor's leaving the mall as people flood in, the first van to arrive is beeping its horn. The horn sounds as if it's passing him (via the doppler effect), but it's coming towards him - no way should it sound like that.

Continuity: The pile of cigarettes Gladys makes as she unloads her groceries changes between shots.

Audio problem: In the shot where David Arquette is at the top of the radio tower he shouts, "You eight legged freaks," but his mouth does not appear to move.

Visible crew/equipment: In the beginning of the movie, when the kid goes for the first time to the spider farm, you can see the camera and crew reflected on the glass of the spider tanks. This is seen when the kid is looking for the owner of the spider farm among the tanks.

Continuity: Something weird happens as the sheriff rolls under the closing gate. She's holding a shotgun before she drops to the floor, rolls under with empty hands (seen from both sides), and as she stands up she's got it back. What's weird is that her dropping and rolling is one continuous shot, so she must have deliberately thrown the gun offscreen as she fell to help her fit through the narrow gap. She doesn't throw it through the gap - we'd be able to see it on the other side.

Continuity: The sign on the door that was blocked by the fork lift truck gets half knocked off by a spider; then you see it intact.

Factual error: In the mine, David Arquette and the others start to smell the methane gas and one of the people even quips "It wasn't me." However, methane is an odorless gas and therefore they probably wouldn't have had any way to tell if it was there.

Continuity: In the scene where the developer goes out to check his ostriches, his flashlight changes size. It goes from large to small, then back to large.

Continuity: Notice when the sheriff hands her daughter the stun gun its metal prongs are pointed down for safety for her daughter, but then it shows a close-up of the stun gun and the prongs are pointed up instead of down. It goes back and forth a couple times doing this.

Continuity: Just after the female sheriff's daughter is attacked by one of the giant spiders there is a scene where the sheriff is holding a double barrel shotgun and hands David Arquette a pump action shotgun. A few seconds later the sheriff has the pump action shotgun and David Arquette has the double barrel shotgun.