Revealing mistake: Bond escapes from the buried pipeline when two technicians open a hatch from the outside. One tech unlocks the hatch by rotating a large wheel which drives the locking mechanism. But when he finally opens the hatch, there's absolutely no mechanism attached. There's just a bare axle that the wheel turns on.
Revealing mistake: When Bond escapes from the research facility, guards give chase on three-wheeled vehicles. One of the guards goes off an embankment & wipes out. He sets the vehicle up and prepares to drive off. Bond is supposed to run up, kick the guard off & take the vehicle. Connery is so slow in this scene that the stuntman has to sit on the vehicle & wait for him to run up for the kick.
Revealing mistake: When Bond is in the trunk of the car, being taken out of the lower level of the Whyte House, a trap door opens out into the desert. The car however does not emerge from the door, which is never seen, but appears to be simply driving along a road. The 'door' is apparently a silhouette cutout raised in front of the passing car.
Revealing mistake: On the oil rig, when Bond tells Tiffany to "shoot 'em" after she gets the gun, three bad guys run towards her. A helicopter drops a bomb in front of them, taking them out, but watch the guy who is the furthest away. The bomb lands a good 20 feet away from him, far enough away not to do any harm. But he crouches a little and stays up, then he looks at his other two crewman a bit puzzled, and then falls down a bit later as he finally realises what he was supposed to do.
Revealing mistake: During the car chase, Bond weaves through a car park, and a police car can't make the turns, sliding into a wall. The wall's covered in one specific point by what looks like a large pale wooden cover, which the police car just happens to slam into exactly.
Revealing mistake: Blofeld is played by an actor that is not bald (Blofeld was bald in 2 previous episodes). He is also played by Charles Gray, who played the part of one of the good guys in You Only Live Twice. [Not really a mistake, given that Blofeld doesn't have to conform to certain physical characteristics. However, an actor playing a good guy then a bad guy over the space of two films rankles a bit...]
Revealing mistake: When Bond wakes up after being buried in the tunnel, there's light coming from everywhere and shining on the walls; yet, there's no direct light coming in from anywhere, nor artificial light sources on the walls.
Revealing mistake: When the orbiting satellite blows up the missile in North Dakota you can see the scientists nearby move freeze in motion.
Revealing mistake: When Bert Saxby is shot there is no hole in his shirt, only painted on fake blood.
Revealing mistake: In the opening scene when Bond pushes Blofield in the mud and we see his legs dissappear, they are obvious dummy legs and the feet have changed position.
Revealing mistake: During the fight between Bond and Peter Franks in the elevator, if you watch carefully when Bond hits Franks' wrist with the door while he is holding the glass shard, Franks drop the glass shard before his wrist gets hit a second time.
Revealing mistake: When Mrs Whistler's body is being removed from the canal in Amsterdam, it's clear in the long shot that it is just a dummy.
Revealing mistake: When the row of missiles blow up near the end, not only are the effects bad but the amount of smoke shown is cartoonish and the missiles are still intact afterwards.