Factual error: The signalling board in the control tower animates train Pelham 123's movements in such detail that the police can tell when it is moving and when it has stopped. Indeed the police deduce that the hijackers have abandoned the train from this. In reality this could not happen. Subway tracks are divided into variable length blocks typically hundreds of yards in length. The signalling boards are only able to show which block a train is in. The only way to tell if a train is moving is when it transits from one block to the next and the only way to estimate speed is how quickly it occupies successive blocks. A slow moving or stationary train are thus not able to be distinguished from the board.

Continuity: Right after the train is hijacked by Robert Shaw at 28th Street station, there are 2 additional hostages in the front car (for a total of 19) that disappear after the train is hijacked between 23rd Street and 28th Street.

Continuity: In the scene where two motorcycles and a police car are driving the ransom uptown to the hijackers, they get into an accident. The car and one motorcycle are wrecked. In the next scene, the same two motorcycles speed off with the money.