Revealing mistake: When the UFO makes the huge flash that knocks everyone in the cemetery down, one of the police officers kicks a tombstone as he falls and it wobbles back and forth. (00:13:35)
Revealing mistake: During the chariot race, where the contestants are riding towards the screen, tyre tracks from the camera vehicle are clearly visible imprinted in the sand. (00:20:50)
Revealing mistake: In the scene where the soldier has to have his leg amputated, when a soldier steps over him, he accidentally hits the knife, which bends, revealing it's a rubber prop.
Revealing mistake: A boulder tumbles towards James Mason and his party though a cave. With all the smashing against the walls and floor of the cave, the boulder stays entirely intact. However, just before the boulder hits a wall with two tunnels while flying through the air, the boulder now shows two majors fractures that were unseen earlier. The fractures were added to the boulder to give it a more dramatic impact by it breaking up with one piece nearly striking James Mason. (00:55:50)
Revealing mistake: Watch the back projection of the Great Northern desert in the train carriage windows. At one point a lorry appears, waiting at a level crossing for the train (that the film was shot from) to pass.