Throughout the film, Martin Scorsese used Xs mostly shown in the background to mark characters for death; examples include shots of Costigan walking through the airport while talking to Sgt. Dignam, Queenan falling to his death (on the building’s glass windows as Queenan falls to the ground), and Sullivan in his office discussing the flow of information with Costello (the X is created by the light shining through the window). This is a homage to Howard Hawks’ classic film Scarface (1932).
Director Martin Scorsese claims that the most important shot in the movie is when Bickle is on the phone trying to get another date with Betsy. The camera moves to the side slowly and pans down the long, empty hallway next to Bickle, as if to suggest that the phone conversation is too painful and pathetic to bear. [x]