Continuity mistake: When Val's bomb gets spat back to the rock and scatters the gang, three of them wind up far away from the rock - too far to have made it in the time of the scene.
Continuity mistake: At the end, as Val and Rhonda are talking, Val's hat brim is flat. Rhonda walks off, and Earl slams the hood of the truck. When they show Val again, the brim of his hat is curved upwards.
Continuity mistake: When Val drives the dozer to get Rhonda off the water tower, he has the bucket up for her to get down. After she's safe, he drives on, and the bucket is down without his having lowered it.
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: 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 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.
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.
Continuity mistake: After Burt reports on the radio that he has killed the graboid in his basement, there are shots of the towns people celebrating. The sky behind all of them is different, specifically the mother and her daughter. In other shots there is blue sky. In these shots there are darker clouds.
Continuity mistake: In the beginning of the movie, watch Kevin Bacon's hair when they're driving in the truck. In some camera shots, his hair is blowing in the wind. In others, his hair is not moving at all. This happens several times.
Continuity mistake: The green fuzzy dice in the guys' truck change over and over. Sometimes they're stuck up behind the rear view mirror, sometimes they're hanging down. Granted, they could fall and the guys could stick them back up again, but in one scene when they're behind the mirror, the faces of the dice that are visible from the front change.
Chosen answer: No, there's nothing illegal about any of the weapons they owned. Some of them may have required a Class 3 firearms license, but even this is not difficult (just expensive) for a law-abiding citizen to obtain.
Grumpy Scot