Plot hole: Even if the white blood cells will attack and destroy the sub and the body of Doctor Martin the atoms would still remain and take normal size after the critical 1 hour is up. This would also apply to the laser gun which they forgot or left behind on purpose, as well as several dozen litres of saline solution which were miniaturised and pumped into Benes' body. He's in a lot of trouble.
Continuity mistake: When the Batmobile is going to park (before the bomb scene) there is a sign saying "Mobey Dick Parking Only". When he is later carrying the bomb and passes by the Batmobile the sign is not there.
Continuity mistake: In the final scene at the sheriff's office, Mitchum has his feet up on the table top, and the boot soles are clean. But after Wayne walks out, there is suddenly a spot on a boot sole. (This is visible in the video)
Visible crew/equipment: In the scene where Jeremy Kemp and George Peppard are playing daredevil in their planes and Kemp's plane hits a brick tower there is a shot of the plane plummeting to the ground. The alert viewer can see the shiny metal wires that were used to support and guide the plane on its way to the ground.
Visible crew/equipment: When Paul Newman takes Julie Andrews up a small hill to explain that he is not going to work for East Germany you can see a shot from a distance. It is clear that this scene was done in a studio, as you can see several lights above the blue background (which is supposed to be the blue sky).
Revealing mistake: As Jango fires the machine gun, the ammunition chain hanging from it is loaded on both sides, and it doesn't move. Also the belt has different sizes of cartridges in it. (00:45:30)
Revealing mistake: Near the end of the film when a building is collapsing and people are running to escape the falling debris, several women along with James Coburn are running up some stairs; a block of cement falls and hits actress Gina Golan right in the head. Instead of killing her on the spot, the bolder merely bounces off her head and she continues running up the stairs. (01:40:55)
Revealing mistake: Although "Man" is supposed to be completely naked, there are several shots where his flesh-colored briefs are visible. Most noticeable when he is initially set loose to be chased.
Factual error: In the scene near the end of the film where Victor Buono is sitting in his chamber addressing his two captives, he opens a can labeled egg foo young with a can opener. He pours the liquid contents into a bowl. Egg foo young is an omelet and could not have passed through the small holes made with a can opener.
Deliberate mistake: When Raza is chasing the "empty" train, as it goes over the trestle just before he stops it, you can see the engineer in the train's engine.
Continuity mistake: When Peter O'Toole is locked in the closet at the museum, he puts a rope through the keyhole and uses a hook to pull it under the door. In the first shot, from outside the closet, the end of the rope is to the right. In the next shot, from inside the closet, the end of the rope slides under the door to the left. (01:22:30)
Audio problem: During the chase at the end of the movie, the police cars' tires squeal in the dirt.
Visible crew/equipment: When Norman is hit by the bundle of newspapers he is thrown in the air and you can see the wires lifting him.