Goofs

During the inspection at the Simpson ranch, when Flanders shows Dave the discolored soil, we see him pick up the dark soil in his right hand and the light soil in his left. When he shows it to Dave, the dark soil is in his left hand and the light in his right. Also, Dave reaches out to sample the soil with his right hand (showing his watch on his right arm). Immediately after, in the following scene, he's holding the soil in his left hand. Later on in the film you see that Dave wears his watch on his left arm.

When Ginny's hand begins to turn to stone, her fingers are straight out, as in a hand wave, but when her hand recovers while within the iron lung, it relaxes from being balled up in a clenched fist.

The flow of silicon is in the wrong direction for turning people to stone. Silicon accumulating in human tissues would make them stone-like; quartz is made of silicon dioxide. In the film, it is claimed that people turn to stone because the monolith monsters steal the human's silicon.

It is often said that, beyond our familiar carbon-based life chemistry on Earth, silicon offers the next most likely possibility. This is because of silicon's ability to make structures from long chains of silicon atoms similar to the way carbon does. Examples of these chains of silicon atoms are pliable silicon rubber compounds. Quartz, on the other hand, is a rigid 3-dimensional crystalline array of silicon dioxide. The carbon-based analog to quartz would be the arrangement of pure carbon into a crystalline diamond.

The town is ordered to evacuate, however when the monoliths reach the bottom of the canyon and someone on a rooftop sees them, you can see there are still many people walking around the town with no indication of evacuation.

When Dave is first discussing the rocks with Prof. Flanders he says that it can't be a meteorite because there is so much of it, but then a moment later he says they have to figure out how to stop it from growing. Simple logic should have told him that a small piece could have grown into much more of the substance.

At 3 minutes Ben stops his overheating Department of Interior station wagon, removes a water container, and opens the hood to reveal a steaming radiator. Without so much as a rag to protect his hand, Ben removes the radiator cap and fills the radiator. Removing the cap from an overheating radiator should result in severe burns to his hand and possible his face.

It is noted that, while the monoliths can turn victims to stone, no one who touches the rock in the aftermath is affected. This could simply be that the monoliths don't become active unless they're hit with fresh water. After they absorb the water, they "turn off" and become inert again. Any people touching them (as shown numerous times throughout the movie) when they are inert would be safe. The first victim's rock was hit by rain, thus making it active when he presumably touched it. The little girl dropped hers in a bucket of water. Unfortunately, the absorption process is never really described (how much contact needed, how long does it take, etc.), so viewers are left to fill in the gaps.

At 1:10 a police car races to what sounds like a screeching stop at the edge of town. As the police car approaches the stop the set of skid marks is already present.

When the camera dollies in on the comatose Ginny, its shadow appears on her.

The autopsy reveals that Ben's petrified body has been "welded into a solid mass" (as if the silicon, in exiting straight out the body, smearing adjacent atoms against each other in the process, diminishing differentiation). This does not account for how Ginny or the farmer's wife regain the use of their hands. Once "welded," the limbs should never have recovered, with the mineral appendage (dead limb) to be amputated in future.

Near the beginning, when Ben stopped his truck in the desert because it overheated, he unscrewed the steaming hot radiator cap with his bare hand, then barely shook his hand as if it caused only a bit of discomfort. In reality, it would have severely burned his hand to the point of causing excruciating pain and needing medical attention.

When Ben, the geologist who has turned to stone when he is first discovered his eyelids move.