Factual error: During the war games they have Jefferson pose as a major in order to facilitate the commandeering of the ambulance and the jeep. Regardless of their personal feelings in the matter the ambulance crew and the driver and troops in the jeep would be perfectly aware that no black man would ever be promoted to a position of authority in an otherwise all white command. We may find it repugnant today but the US Army was rigidly segregated during World War 2 - and it stayed that way until 1948. Jefferson may have been inducted into a special unit like the Dirty Dozen but considering that the future of the entire mission is riding on their success at the games, throwing it all away like that makes no sense at all.
Factual error: When M and his entourage arrive at Bond's estate their cars are surrounded by sheep. They then drive on down a unsurfaced road to Bond's house, past a pride of lions he keeps on the grounds. A series of sweeping overhead shots shows us it is all one huge field, with no fences or the like. Those sheep aren't going to last very long.
Continuity mistake: Jim Dale and Anita Harris think that Barbara Windsor is going to jump off the roof and race across the road into the nurse's block. We see Anita Harris is wearing dark seamed hosiery as she runs up the stairs. A few minutes later she hangs down from the roof and the seams have disappeared from the backs of her legs. (00:59:00 - 01:01:55)
Visible crew/equipment: After Lucifer talks to God and doesn't know what is happening and Saint Peter comes to escort him out they get into a discussion why he failed the entrance examination, you can see a reflection in glass between the camera and Lucifer and a man who does not appear to be St. Peter. (Maybe director Stanley Donen?) (01:39:25)
Other mistake: After the "fat fat fatty" scene, Franz shoots his way in, starting with three bullets into the door lock. Over the next scene he fires about twelve shots, despite the fact he's firing an 8-shot Luger.
Continuity mistake: Millie's beads have a mind of their own. They do not stay in place even when she is standing still. Besides the funny scene during the title credits (when it is deliberate), and when Miss Dorothy registers, they also move during a scene when Millie displays her thoughts on Miss Dorothy's beads when the two of them go into the elevator for the first time.
Continuity mistake: In the scene in the bullring, Fathom is knocked down by a pursuing bull. We see black underwear under her dress after she falls down. She gets knocked down a second time shortly after and this time it has changed to white.
Factual error: The problem with firing a cannon on steam power is to have the boiling water build enough pressure inside the barrel, with no leaks or openings to release it before its time. The professor's scarf and the plug hammered into the fuse hole (which also flies off just before the shot) wouldn't be good enough as pressure restrainers.
Revealing mistake: During the pie fight sequence Brenda is obviously wearing a wig as her hair suddenly becomes twice as thick as it was before.
Continuity mistake: During the dinner sequence, Angela Douglas is handed a letter. She is seen holding it with her right hand, but when the man seated next to her asks "What is it, my beloved?" we cut back to Angela and she is now holding the letter with her left hand.
Continuity mistake: Pauline is driving in the one-way street, of course the wrong way. There are several continuity errors between cuts; for instance when you see the 'boy' in the back seat laughing hysterically behind her, in the background you can see the red pick-up she nearly has a frontal with in the next shot. (00:05:00)
Continuity mistake: The Packard convertible stolen at the beginning can be seen with and without a rear window during the chase scene.