Factual error: At the East German / West German checkpoint, there is a level crossing. The warning signs for road traffic are clearly visible and are unique to the UK (where the shot was filmed).
Plot hole: When Bond is on the roof of the train ,he opens the roof panel on the rail car, jumps down into the car, and puts on a gorilla suit to hide. He does all this while the knife thrower is in the small car. Wouldn't the knife thrower have heard something? The roof panel opening alone would have amplified the train's noises, not to mention the air that would have blown in.
Continuity mistake: When Bond is taking off with his Mini-Jet he nearly hits the jeeps and trucks that are chasing him. The landing gear is still down. After the cut you can see the scene from the other side and now the gear is suddenly up. There is no interruption between the two shots, not even the two or three seconds the gear takes to retract.
Factual error: Bond tells Q at one point "I've lost my PPK." However, he has been carrying a Walther P-5 throughout the movie, and continues to use it in the later action sequences. A PPK never does make an appearance in the movie. The P-5 was also used that year by Bond in "Never Say Never Again").
Revealing mistake: In the scene where Bond is trying to escape with his new Mini-Jet, he flies through a big hall. If you look carefully, you can see that the aeroplane which is supposed to be flying with its wings vertical is fastened to some kind of sustainer.
Revealing mistake: When Bond and Gobinda are fighting on top of the train, Gobinda rolls over with his sword, which bends like a rubber prop.
Revealing mistake: When the police cars chase Bond and stop outside the circus, you can clearly see a lot of brake-marks. It's quite obvious that the filmmakers re-shot the scene several times, before they got it right, but didn't bother to remove the marks made in earlier takes.
Revealing mistake: When Gobina first slashes at Bond during the climactic fight on the plane, a subsequent medium shot reveals a stunt double (note the bald spot). He's even wearing completely different clothing - a black stunt suit instead of a blue jacket and white shirt. (02:05:00)
Other mistake: When Bond drives into the train tunnel, below the train cart with the jewelry, we see that welding is going on in the other train cart. But that is before the bomb is placed in the hole below the cannon. There is no sign of weldings, and no sign of welding equipment once we get inside that cart.
Factual error: On the railroad when the knife-thrower is welding the jewel canister onto the circus equipment, there are bright flashes of light. Later however, the knife-thrower attacks Bond with a gas welder. Oxyacetylene torches (gas) merely heat the metal until it melts. They do not produce blinding flashes, unlike arc and MIG welding kits (electric).
Factual error: In some scenes, the Communist soldiers use the wrong armament: the Cubans use American M16s (whereas they should be using AK-47s), and Orlov's bodyguards (in the scene where the jewels are switched for the bomb) have Austrian Steyr AUGs. It would have been rather problematic for socialist countries (during the period of the film) to keep captured Western weapons constantly supplied with spare parts and ammunition.
Continuity mistake: When we see Q fishing, the lighting is totally different from when he's seen from the back in the next clip. Also the bank rises close behind him when seen from the front, but in the next clip the camera position is further back. Those are not shot in the same place. (01:09:30)