Goofs

The astronaut has no heartbeat and no respiration, but does have blood pressure. While this is shown as a scientific implausibility, it's not explained how the doctors can detect the astronaut's blood pressure without a heartbeat. Blood pressure readings using a sphigmomanometer (blood pressure cuff) rely on the heartbeat to determine both the systolic (which is the pressure of a compressing heart) and diastolic (which is the pressure of a relaxed heart). In other words, no matter what technobabble you want to offer, there's no way to determine blood pressure without a heartbeat.

Any engineer should know that you should not light a cigarette near any crashed vehicle because of the hazards of flammable liquid or fumes from spilled fuel.

A close-up of the bottom half of the creature reveals that its feet are actually shoes.

Dr. Julie Benson refers to Steve Dunlap ('John Baer') as "John."

When Steve runs into the cave after the creature, the sound indicates that he is really running on a wood floor.

During some shots, part of the camera's for-end is visible along the top of the screen. Possibly due to a problem with the lens mounting.

In the beginning, when they find the rocket crash site, several views of the area show it to be very mountainous, with winding roads cutting through steep rugged hills. Later, one of the characters mentions they are in Florida. Florida is comprised of flat terrain. There are no mountains or natural hills in Florida.

Several characters refer to Steve Dunlap as John or Johnny (the actor's name).

Poster is totally misrepresentative: It shows an entire head being ripped off. In the movie it's only half a head. It shows a scantily clad woman shrinking from a wave of blood. The woman menaced in the movie sees no blood from the monster and is dressed in her work clothes as a field photographer, a khaki suit with long slacks and jacket.