Revealing mistake: In the scene where the launch platform is moving in Blofeld's cave to move the rocket to the Volcano crater for launching, there is a close up of the platforms wheels. Some are moving in the right direction,others aren't moving at all,making it look like the plastic model that it was. If it was a real platform, the weight alone would have made all the wheels turn in the same direction.
Revealing mistake: At the beginning of the film during Bond's "funeral", the shot cuts to a man watching the funeral from a boat through a pair of binoculars. The camera then moves to the newspaper next to him showing an "article" reporting Bond's murder. If you look closely at the "article" itself, you can see it was actually pasted onto the actual local newspaper. They probably bought a local newspaper and pasted the fake article over it to make it look authentic.
Revealing mistake: Upon capturing the Soviet spacecraft, SPECTRE's spacecraft does some attitude maneuvering with small rockets on the side of the hull. The rockets fire visible exhaust from screen-left to screen-right, but flecks of the stuff slow to a halt and accelerate backwards, right to left, exactly as if the spaceship model were standing upright with the camera tilted sideways, which is exactly what was done.