Continuity mistake: When the worker is drilling the ground you see his mouth is clean. When it cut, his mouth is now covered in mud. (00:17:15)
Continuity mistake: When Valentine climbs up to get Edgar you can see a green mark under Edgar's shoes. When we see Edgar lying in the car the green mark is gone. (00:13:40)
Continuity mistake: When Val and Earl are relaxing with a couple of cold ones after they bury the trash, Val's recliner chair changes. From the side it is a brownish-rust color cloth material. In the next shot, from the front view, it is greenish leather. This scene takes place after Rhonda's near miss with the graboid but before the first guy, old Edgar, is found dead.
Continuity mistake: When the "graboids" are testing the buildings, they test the house with the mother and daughter on it. Watch the sky in the background. It goes from sunny to overcast, then back to sunny in a matter of seconds.
Continuity mistake: Near the end before Val throws the last bomb,. He twirls the fuse leaving a stub left, which Rhonda lights. Val throws the bomb, and the fuse has grown a few inches. (02:00:00)
Continuity mistake: Reba gets out of their truck at the compound and looks through the binoculars - in the foreground you see the tractor and trailer they use to escape are very close together, or are attached already. When Kevin Bacon and the other guy figure out to use it, the camera pans around and the tractor and trailer are 60-100 feet apart.
Continuity mistake: When Walter names the monsters Graboids he puts his hands down. When it cuts he holds both arm against his waist. (00:45:05)
Audio problem: When Val gets the Cat running he cheers out loud. It cuts to a shot looking up at him inside the Cat, he cheers again but his mouth is closed. (01:10:00)
Continuity mistake: At Dr. Jim's when he is standing by where the generator should be, you can see several items around. When it cuts all the items has moved. (00:22:40)
Revealing mistake: When the graboid starts pulling Jim underground, his wife hands him a board to keep him above ground. You can see the thick board bend rather easily while his wife hands it to him. Also when Jim is sucked under ground it bends quite easily as well, as if it were styrofoam.
Revealing mistake: When Earl and Rhonda are being chased into the store and they're running along the little boardwalk, the boards are forced up like a wave by the snakeoid. But the ground under the boardwalk is perfectly flat.
Visible crew/equipment: Towards the end, just after Kevin Bacon says "this one's not falling for it," watch for a boom mike right at the top of the screen.
Continuity mistake: When the trailer is being dragged by the bulldozer, the wheels rotate. The trailer would need an air hookup to make it happen, otherwise, the tires won't rotate.
Other mistake: Once Earl stops the CAT at Burt and Heather's house, Val is standing on its roof directly above Earl. Val is looking and talking straight at them. The graboids shake the CAT, Earl drives it forward quite a bit (take notice just how far), but he looks up to tell Burt to hurry but he and Val are still facing in the same direction. They should be facing backward due to the distance they had to move up. Also, you'll notice that Burt is right in line with the trailer as he throws most of his gear. (01:14:30 - 01:15:30)
Continuity mistake: When Burt and Heather are fighting the graboid in their basement, shortly after Heather yells "Magazine!", one of the large revolvers between them falls off the rack but is replaced in the next shot.
Factual error: When Val is talking to Burt on the CB radio and desperately trying to tell him to get out of his basement, Burt is using a handheld CB. After Val's very last transmission, Burt is now holding a rifle, not the CB. When the Graboid crashes through Burt's basement wall, we hear him say over Val's CB, "Jesus Chr..." his transmission was cut off. First of all, Burt wasn't holding the CB so he wasn't transmitting at the time. Second, there are portable CBs that you can lock the PTT button for extended transmissions (I owned one), but that wasn't the case here. Finally, even if by some chance Burt accidentally did lock the PTT button before putting it down, it wouldn't have cut off. The Graboid broke through away from where Burt was standing and talking and couldn't affect the CB. It was done for dramatic effect of the scene. (00:58:30)
Suggested correction: Could be he put the CB down on the PTT button (it's a rather large one) and it stopped transmitting when the tremors caused it to flip off it.
Visible crew/equipment: As the camera pans up to the roof of Bert's house, a film crew member is reflected in the window.
Continuity mistake: When Val is getting the fuse lit on his bomb to throw to the last Graboid, we see his hands separated, one holding the bomb and one holding the rope. The camera angle changes to a close up of his hands, where they are now both holding both the bomb and rope. (01:24:50)
Revealing mistake: When the graboid goes to launch out of the side of the cliff, you can see the wall is fake because it moves in and out right before it breaks through.
Revealing mistake: Given that the store is a set to move up and down to simulate the graboid attacking it, we can actually see the store's brick walls bouncing in the shot before the effect was used.
