All great films have some mistakes.
While Val and Earl are running along side a wire fence, being chased by the Graboid, you can just barely see a stage-hand pulling one or two wooden posts from the ground.
When the little tractor thingy is driving itself, you can see the rope that is pulling it for a split second while it is falling down.
It is pretty amazing that even after spending the night in the desert, when Rhonda wakes up the next morning, she still has make up on!
While Rhonda talks with Val at the end of the movie her hair is brown and dry. After she walks away Val goes after her for a last kiss. At this point her hair looks wet and a much darker shade of brown.
When the old Fred is raking his garden you can see his blue car sitting in the driveway, but when Val and Earl go to his house to check on him after the creature came the car has vanished.
In the scene where they are about to jump into the truck trailer if you look closely you can see the back of someone crawling behind the bulldozer’s tread.
After the doctor's wife jumps into the station wagon to drive away after her husband disappears into the ground, she reaches to turn the key in the ignition but there are none. Soon after, however, as the car is being dragged downward, she hits the steering column in panic and the lights turn on. How is this possible without the keys?
Heather's position changes when the tentacle is discovered under Earl's truck.
Tremors 2 bloopers:
At one point you see the door of the Volvo is open after it is pulled shut.
Earl's shirt is dirty from being pulled by the ostrich until he turns around.