Factual error: In Blofeld's offshore control room there's an Earth-globe turning under a model of the satellite, to illustrate its orbital groundtrack. The way it's arranged, however, shows an orbit which is impossible. It shows the satellite tracing a groundtrack over a constant latitude. The only instance in which this is possible is if the orbit is directly over the Equator, whereas the model shows it over a latitude well within the Northern Hemisphere.
Continuity mistake: In the opening sequence when Bond runs over and pulls the chain to release mud onto the guy rising up to shoot him, mud clearly splatters all over him as he dives to the floor. When he gets up, his suit is spotless.
Continuity mistake: When the car chase enters a car park there is a blue car in the bottom left corner (from the overhead shot), next to the trailer which Bond makes his escape over. After Bond escapes the car is white (I think) and may also be pointing the opposite direction.
Other mistake: When the man at the start is thrown through the room and his head hits the wall, the picture briefly freezes.
Visible crew/equipment: When the helicopters are attacking Blofeld's platform, at some points you can see a little black spot moving in the background. It is the radio-controlled helicopter which filmed them from behind.
Continuity mistake: Bond shoots the Blofeld-copy with a climbing hook. But when did he reload his gun? (And why? He was done climbing).
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...]
Factual error: When Bond is in the trunk of the car, being taken out of the lower level of the White House, a trap door opens out into the desert. There are two Saguaro cacti shown, one on the trap door and one in the distance. Saguaro cacti do not grow wild any where near Las Vegas.
Continuity mistake: In the battle scene on the oil rig, Bond takes takes control of the crane attached to Blofeld's bathosub. During this sequence the folding window at the front of the crane cab switches between the raised and lowered position several times. (01:47:53)
Factual error: When Bond is inside the oil rig, the shots switch from the satellite control room to the satellite itself orbiting. When the satellite fires at the underground missile, it's orbit direction reverses. Then, when it fires at the Russian sub and the Chinese military base, it stops before it fires. This is impossible, as Newtons 3rd law states that for every action there is an equal and opposite reaction. For the satellite to reverse or stop, boosters would be needed at the front of the satellite (of which there aren't any) to counter it's speed. And even if they were there, the direction change and stop wouldn't be as sharp as the movie shows.
Factual error: When Mr. Wint and Mr. Kid assassinate the doctor in the South African desert, they use a scorpion. Scorpions are poisonous, but the sting is more like a bee's, and woudn't kill a healthy adult.
Plot hole: When Saxby tells Blofeld to watch Peter Franks on the CCTV, Blofeld would have recognised him as James Bond. Why does Blofeld keep quiet about it? What possible use could he have for catching, rather than killing, Bond? (00:38:34)
Other mistake: When the car chase starts in Vegas in a close up of the two policeman chasing them the driver is wearing sunglasses and the background is badly dubbed. Silly thing to wear when it's nighttime.
Audio problem: Peter Franks drives a Triumph Stag, which used a 3 litre V8 engine and had a very fruity exhaust note. Unfortunately this was dubbed over with a rather weedy 4 cylinder engine sound.
Continuity mistake: When Bond and Tiffany are having their dinner on the cruise liner, Bond makes comments about the wine and you can see behind him there is a liquor bottle on the food cart with a large white label facing the camera. When Bond is being strangled by Mr Wint and reaches for the bottle to smash and throw the contents at Mr Kidd, the bottle is turned and the label is facing away from the camera.
Plot hole: Glass or paste stones would have melted during Franks' cremation. But we're supposed to believe they ended up in the urn. (00:33:38)
Continuity mistake: In the opening scene Bond smashes the giant light on top of Blofield and he falls across the table, but in the very next scene when Bond fastens the strap, Blofield is lying horizontal to it. This is a continuous scene.
Continuity mistake: When Bond shoots a Blofeld look-alike, he falls onto the couch, but in the next shot he's on the floor. He couldn't have rolled off the couch, because he's on his back on both the ouch and the floor, and we don't hear him hit the floor.
Revealing mistake: When Saxby is shot, he has an instant, pre-dried blood splatter on his shirt.
Chosen answer: Blofeld and Spectre has enough diamonds for the laser he is building to hold the Earth hostage. In typical Spectre fashion, since he is finished with the operation, he wants to leave no loose ends that could tie Spectre into the mix.
Zwn Annwn