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.
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").
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.
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.Jacob La Cour
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.