When Scorsese first received Paul Schrader’s script, he didn’t feel it necessary to make many major changes for the film. He immediately connected with what Schrader had written, saying that he “reacted very viscerally, almost mystically to it and its tone and the struggle of the character.” However, he did change some of the plot's sequencing in order to heighten the drama and give it a more logical flow. For instance, in the original script, Bickle went straight from applying to be a taxi driver to working as a taxi driver, but in Scorsese’s movie, Bickle is shown at home after he applies for the job. This extra scene allowed Scorsese to develop the character of Travis further in the beginning of the movie. By showing Travis writing in his diary, Scorsese justified the liberal usage of voiceover throughout the film.
Scorsese is known as an intelligent and artful director, as well as for his ruthless and grisly depiction of violence. Scorsese solidified his reputation as a skillful director of violence with the final scenes of Taxi Driver. Scorsese’s now famously visceral and bloody style served to heighten the intensity of Travis's final confrontation, when the story moved from script to screen. Scorsese also added De Niro’s iconic mohawk-hairstyle for the end of the film after he talked with a friend who had come back from Vietnam. His friend told him that when a soldier had their hair cut like that, it usually meant they were about to go on a Special Forces operation, and were ready to kill. Thinking that that was exactly the image that Bickle’s character would want to portray, Scorsese added it into the film.
Scorsese and De Niro's relationship made for a rich creative collaboration. Trusting De Niro with the task of bringing Travis Bickle to life, Scorsese turned on the cameras and told De Niro to talk to himself in the mirror. This improvisation led to one of the most iconic lines in movie history, as Travis smirks and asks his own reflection: "You talkin' to me?"
