Robert De Niro prepared for the role by working as a late night cab driver in New York City early 1975. One of his fares was a struggling actor who recognized him from The Godfather Part II (1974). The young actor said to De Niro discouragingly "Wait a minute, you just won an Oscar. My God... is it THAT hard to get work??"
Robert De Niro has said that despite having won an Oscar for The Godfather Part II (1974), he was still a relatively unfamiliar face, and was only recognized once while driving a New York cab during his research for this film.
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; this shot also showcases his isolation and loneliness.
Robert De Niro worked fifteen hour days for a month driving cabs as preparation for this role. He also studied mental illness, and during his off-time when filming 1900 (1976), visited a US Army base in Northern Italy and tape-recorded conversations with Midwestern soldiers so that he could pick up their accent.
When Paul Schrader was first writing the script, he believed that he was just writing about loneliness, but as the process went on, he realized he was writing about the pathology of loneliness. His theory being that, for some reason, some young men (such as Schrader himself) subconsciously push others away to maintain their isolation, even though the main source of their torment is this very isolation.
Victor Argo: As shopkeeper Melio who is held at gunpoint by a robber (Nat Grant), who is shot by Travis Bickle (Robert De Niro), thereby saving Melio.
Martin Scorsese: Sitting down, behind Betsy as she walks into the Palantine campaign headquarters in slow-motion.