Continuity mistake: In the scene towards the end of the film where we see Slade's body fall, it falls onto a submerged rock just below the surface of the water and there is a splash of water. In the next shot Tarzan looks down from the cliff above and Slade's body is on a large dry rock, a little distant from where the body originally fell.
Continuity mistake: At the beginning of the scene where the pilot's wife is attacked in her bedroom by (not) Bela Lugosi, look at the pictures on the wall above the bed. After the attack begins, the pictures are different.
Continuity mistake: Ben-Hur places his crown on a table when he visits the fallen Messala, but upon returning the table and crown are gone. (00:36:35)
Continuity mistake: When Colonel Marlowe blows the bridge near the end of the film, a pair of spectacular explosions ensue, tossing planks and beams into the air. However, as Hannah Hunter gazes at his retreating form, the bridge is still intact.
Continuity mistake: When in James Mason's house in South Dakota, Cary Grant writes a message to Eva Marie Saint on a matchbook from which several matches are missing. When Ms. Saint subsequently reads the message the matchbook is full.
Continuity mistake: The escape train stops at a station at which another train has been the site of a massacre. One of the victims of this massacre has his head leaning out of a railway carriage window. As Kenneth More and Lauren Bacall from the escape train walk about the station, he can be seen raising and then lowering his head again as he realises that the 'take' is not complete.
Continuity mistake: After the villain (Thayer David) kills a duck, a boulder begins to move and brushes the side of his right leg as seen in a close-up and both legs can squarely be seen as he is standing beside the rock. The scene changes to a stunt-man who has his left-side towards the camera and this time his right leg is closer to the boulder which pushes him over a ledge. (01:50:35)
Continuity mistake: The background shots of the Matterhorn show it with a clear sky, then a cloud around it, then a clear sky again. This keeps happening.
Continuity mistake: When the MR-1 first lands on Mars, the sky visible through the portholes is fiery red, which is the uniform color of all exterior shots in the film. However, a whole series of interior shots throughout the film show that the sky visible through the portholes is suddenly and inexplicably baby blue. At two points, when Iris sees a Martian through the porthole, the sky momentarily turns pitch black.