Goofs

Depictions of earthquakes are accomplished by merely shaking the camera. While the scientist group moves about when the earthquake strikes, the sailor group doesn't move around at all.

At the start of the film, the landing boat has ten people in it. Moments later Lt. Quinlan says the boat is bringing more supplies. This is the same landing boat. How could it have gone back to the seaplane so fast and returned? Also the amount of people has increased. One Seaman too many.

When the scuba divers are rising to the surface (from the underwater camera shot), the water depth appears to be over 25 feet, yet when the camera angle changes to above, the divers immediately stand up after surfacing.

When Deveroux calls out to the first team upon arriving at the island, the echo does not match what he shouts.

When the first crab attacks dale, he goes into the room where the noise is coming from and the door swings inwards, but when he runs out of the room the door also swings inwards.

In describing the two biologists, Hank Chapman says that the man takes care of land animal-ism and the woman handles the seafood. A biologist's duty would not be referred to as "seafood."

Wheels and legs under the giant crabs.

As Martha, swimming in the sea, approaches a giant clam on the sea bottom, a square reflection can be seen on the glass of the tank she is actually swimming in.

When Martha and Dale come out of the water after their swim, a crab is shown on the beach with a string tied to it.

During the opening scene when the sailor tumbles off the boat into the water, the boat is nearly at the shoreline. But the underwater shot shows him to be at least 10 or more feet under water before he is decapitated by the giant crab. Also, the crab could not possibly have been lurking unseen near the shallow water of the shoreline.

Although Richard Garland's character is called "Brewer" throughout the movie, the end credits spell his character's name as "Dale Drewer".

Although Ed Nelson's character is listed in the credits as Ensign Quinlan, he is referred to by Dr's Hunter and Weigand as Lieutenant Quinlan.