Factual error: The "B" train which he is chasing normally runs on the right most track (there are 3 tracks on this particular line). The middle one is never used except for out of service trains. Most of the train stations on that line service the right or left track, not the middle one.
Factual error: In the beginning of the movie when the Frenchman is shot in the face, his face is instantly a mess of blood. In reality, an entrance wound from a pistol shot is a neat little hole (i.e. blood splatters from the bullet's exit wound, not the entrance). It would take awhile for blood to cover his face.