The opening view of the Carpathian castle shows a starry sky. Stars are again seen through the telescope opening in the observatory roof. But there is highly inclement weather in other parts of the opening scenes. Diana and Mother Rukh are witness to much lightning and thunder. Plus, there is fog and howling winds when the car arrives with Dr. Benet and company.
When Janos writes a note to his wife with the headman holding a box to write against, the note is about 6 inches wide and maybe 5 inches tall. When Diana reads the note in the tent, it is much larger (closer to 8-10 inches wide).
After both the old guy and the woman sitting next to him have both refused to be served any antelope stew, there are several camera cuts, but none indicating passage of time. In the next close-up of them, when someone has brought the woman a letter, these characters now have a small plate of antelope stew right in between them.
1 hr 5min into the film, while they are trying to figure out who is doing the killings, Bela Lugosi is sitting down and crosses his legs; there's a quick camera close-up to him and back to the long shot: his legs are then uncrossed. Bela speaks a few lines, and again crosses his legs in the long-shot, as if for the first time.
When Karloff threatens the African men, they crouch down but, as the camera cuts back and forth to the actor and back to them, the men go from crouching to standing up, back and forth.
The image of Earth projected by Janos Rukh is stated to be that of the planet as it appeared millions of years ago. This projection shows the continents in their modern configuration. But the continents have shifted radically during the past and would have looked entirely different from they way they do today.
The wedding scene between Frank Lawton and Frances Drake takes place in a Roman Catholic cathedral in France, but the text of the wedding service ("With all my worldly goods I thee endow") is taken from the Book of Common Prayer of the (Protestant) Church of England.
The name Janos in Hungarian is pronounced "Ya-nos" but everyone pronounces it like the Arab name, Yanoush (yah-noosh).
After Bela Lugosi takes an ultraviolet photo of the eyes of the deceased Sir Francis Stevens and turns out the bright light, Sir Francis is clearly seen blinking his eyes and moving fingers on his right hand again.
The story is frequently advanced by the old "newspaper headline" gimmick. About 45 minutes in, one newspaper tells of the "Benet expedition," but in the small print the name is misspelled as "Bennet."
The film shows a clipping from a news magazine announcing that the principal characters have gone on an expedition to Nigeria to find the meteor containing Radium X. Yet in the earlier sequence showing the meteor landing on earth, it hit on the southwest coast of Africa over 1,000 miles away from Nigeria.
As Dr. Rukh begins the projection of the ancient meteor impact, he shows a zoom sequence that passes the great nebula in Orion on the way to the Andromeda galaxy. Those two objects are found in completely different constellations and, therefore, different parts of the sky. A zoom sequence that aligns them is not correct.