This Island Earth (1955)

Character mistake: After Cal goes to the secret lab in Georgia, he and two others go into his new lab. When they enter a cat jumps up on the counter. Dr. Adams says "This is Neutron. We named him that because he's so positive." Neutrons are neutral and electrons are negative. It's protons that are positive. They should have named the cat Proton.

mrfrede

Continuity mistake: Shortly after the movie starts, Cal's plane lands and they go into the lab. Cal looks through a scope at an experiment and his assistant is next to him without glasses. After the experiment flames out, they show the men again but now his assistant is wearing glasses. (00:08:50)

mrfrede

Continuity mistake: Three scientists escape from the lab. The car stops and two get out and go into a pond surrounded by water. They dip under the water as the car explodes. When they come up they are still surrounded by water. Next, the German scientist shows up and they dip under the water again. After the explosion the camera shows the two in the pond again but now they're surrounded by reeds.

mrfrede

Trivia: In the shot where scientist Cal Meacham is pulling the power plug from the Interocitor, the post supporting the triangular viewscreen is suddenly taller than in it is in any other scene. It appears to have been lengthened deliberately for this shot in order to raise the viewscreen above the top of the film frame. (00:20:40)

orzel-w

The Monitor: It is indeed typical that you Earth people refuse to believe in the superiority of any world but your own. Children looking into a magnifying glass, imagining the image you see is the image of your true size.
Dr. Cal Meacham: Our true size is the size of our God.