Revealing mistake: When all four actors are up on the rooftops, look closely at them when they all step onto the smoke platform that brings them down. All four actors are doubles. (01:46:50)
Revealing mistake: When the genie (Burl Ives) moves the fire plug you can see a bracket holding it up and running down to a track beneath it.
Revealing mistake: Near the beginning, Hengist and Horsa are watching a young cave couple dragging each other around. Hengist is pouring Horsa a drink and you can see him pour, raise the jug, then Horsa takes a sip from his cup. All this time it is patently obvious that no liquids are in the vessels.
Revealing mistake: In the sequences where Mandrake and Ripper are under attack by the US Army, we see exterior battle sequences in front of the base. However, no matter how many bullets are fired at the building, all the windows remain intact.
Revealing mistake: In their hotel room Ringo says, "Do I snore, John?" If you look at Paul's hands on the piano it's obvious that he's not playing and that it's an over-dub that we are listening to. (00:17:30)
Revealing mistake: When our heroes are on the conveyor belt which carries the rocks towards the spinning saw blades, the rocks which get cut in two are seen to be cut before they reach the blades. (01:20:45)
Revealing mistake: When Brando poses with a group of young women for a picture, we can see two signs in the background, "Hotel Deutschs-haus" and "Bayerishe Verein" - both of them in grammatically bad German. Correctly the signs should spell: "Hotel Deutschhaus" and "Bayerischer Verein".
Revealing mistake: When Mr Chipfield is coming down the stairs in the bath tub, you can see it is an obvious double for Leslie Phillips.