When Bill and Helen Wilks, with their daughter, arrive at the train platform, there are a lot of signs behind them. Then, in a long shot, just before the train pulls in, what is behind them is completely different - just a blank wall with windows on top.
At the end, as the soldiers leave the train, Beau Bridges' top coat is left on the seat. In the reverse angle, as everyone else leaves, the coat has disappeared.
The travel time, as shown, in going from one station to the next was far too long to be realistic for the NYC subway. Normal travel time is usually under five minutes between stations.
When the train enters the tunnel or goes underground, it is a newer model, not the older model with the wicker seats. This train has round windows at the end of the car and lit up train numbers.