Factual error: The signalling board in the control tower animates 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 moves from one block to the next and the only way to estimate speed is by how quickly it occupies successive blocks. A slow-moving or stationary train are thus not able to be so easily distinguished from one another on the board.