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: In the shooting scene in the Mount Rushmore cafe, a boy in the background puts his fingers in his ears, because he knows the gun is about to be shot.
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: The bullet hole gouge in the window frame near Ricky Nelson and the outward facing splinters at the bullet hole in the door frame near John Wayne indicate exit holes.
Revealing mistake: In the scene where the girl is going to shoot Vincent Price watch closely as she pulls the trigger. You can see the wires pulling the gun from beneath to give it the realism of the blast.
Revealing mistake: During the opening credits, as a crab descends past the periscope, the string attached to the crab is visible.
Revealing mistake: When Spats Columbo's gangsters are being searched for weapons at the Florida Hotel, the man doing the pat search can be seen placing the gun behind the gangster's leg, just before it supposedly drops out of his trouser leg.
Revealing mistake: Rock Hudson angrily picks up Doris Day from her bed, blanket and all, and carries her through town to his apartment. When he is walking down the sidewalk, the blanket slips and the supporting wooden board underneath Doris Day is visible. This made carrying her easier.
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.
Revealing mistake: Near the beginning, when police Lieutenant Rowan is inquiring on the death of Ken Drake, there are only 4 men in the room, all facing one another in a wide shot. The camera cuts to a close-up of Dr. Bradford for a couple of seconds, and there is a distinct puff of cigarette smoke passing behind him, but none of the characters in this scene are smoking. Lieutenant Rowan does smoke later in the film (in fact, he's the only character who smokes), but he's not smoking in this early scene. Apparently, the close-up of Dr. Bradford was borrowed from omitted footage in which Lieutenant Rowan was smoking.
Revealing mistake: When Wilby is in the car being chased by the police officers while he is a dog, in some scenes the dog is a real dog and in other scenes it is just a person in a dog costume.
Revealing mistake: A driver pulls out into oncoming traffic and hits another car, It is obvious that when the scene was filmed, the driver stopped just short of the other vehicle. The sound effect of a collision is dubbed in and the front of the two vehicles is never shown.