Revealing mistake: In the scene at the end when the sub explodes, you see the hull split in two and the propeller drops away. But you do not see the prop shaft.
Revealing mistake: When Bond goes skiing with Electra to check the pipe lines, in one scene you can see ski tracks in front of the pair. They could be from previous line inspections, but surely they would have been snowed over? That area doesn't look like a popular ski resort....
Revealing mistake: During the ski chase, a paratrooper pulls out a submachine gun and fires a volley of bullets at Bond. However, as these hits the ground, you can see that actually there are two parallel lines of explosions behind Bond. The submachine gun can't possibly shoot two regular lines of bullets like that. (01:37:00)
Revealing mistake: Right at the beginning of the boat chase when Bond drives the boat through the waterway in MI6, before he jumps the boat into the river, there is a shot roughly from Q's POV, the boat clearly slows right down before it reaches the end. It couldn't fly as far through the air as shown.
Revealing mistake: During the action sequence on the labyrinthine docks on the Caspian Sea, one of the choppers with the rotating blades saws Bond's BMW in half. A cutaway shot reveals Bond nearby, murmuring, "Q's not gonna like this." The next shot is in back of Bond, seeing the newly split BMW fall apart, but Pierce Brosnan has been replaced with a dummy. This is most obvious during the over-the shoulder shot of the BMW falling apart, where Bond's gun is now held in front of him. Also, when the car splits in two, the dummy shakes a bit.
Revealing mistake: In the boat chase, Bond decides to dive below the barrier. It is very close to him, but takes about 5 seconds to dive. He would have hit it in about 2 seconds.