After Travis walks out of the building, we are greeted with a very interesting shot. Travis is walking in the opposite direction of each and every taxi parked on the curb. This is an early indicator that something about him is off and he goes against the grain of normal society.

This was intentionally changed by Scorsese into a Marine jacket, as he felt the character would resonate more if Travis was a Marine. There is evidence later in the film that confirms Travis was indeed in the Marines and not the Army.

This is an allusion to Luke 2:18-19, which reads

And all they that heard it wondered at those things which were told them by the shepherds. But Mary kept all these things, and pondered them in her heart.

This is another example of Schrader translating his experiences is Los Angeles into New York. “Real” Don Steele was a famous DJ for KHJ, an “ultrahip” radio station in Los Angeles.

He was known as slick and confident, which would definitely annoy a loner like Travis. And based on how he was written into the screenplay, he must have rubbed Schrader the wrong way as well.

This is almost the same exchange, verbatim, that Travis had with Betsy as he was leaving the campaign office.

TRAVIS: And… ah… Betsy…

BETSY: Yes?

TRAVIS: My name is Travis.

BETSY: Thank you, Travis.

This strongly suggests that Betsy’s rejection has spurred him to find a new “angel” to obsess over, and that his decision to save Iris stems from this event.

What Travis seems to be hoping for throughout this movie is an almost Biblical flood that will wash away all the sinners he sees on a daily basis. But he also hopes that the rain will help achieve redemption and rebirth for characters like himself and Iris that got caught up in the filth and are looking for a way out.

The TV is important to Travis because it is really the closest thing to a friend that he has. It lets him form what is, in his mind, a connection with the various characters he sees on TV. So breaking the TV and completely cutting off the minimal contact he had with the outside world essentially sealed his fate.

Despite what he tells us, and despite the fact that “spook” is the most overt display of racism we get from him, Travis Bickle is hugely racist and it shapes the way he views the world.

In the original screenplay, this point was made more clearly, as every character that Travis ended up killing was black. This was changed to appease the studio, but Travis' underlying hatred for blacks remains. This is reflected in the way he glares at most black characters he sees, whether it be in the streets or in his pornos, and in his indifference to his racist passenger’s intention to kill his wife for sleeping with a black man.

In the movie, this was changed to a Mohawk. This was suggested by Victor Magnotta, a friend of Scorsese who worked in the Secret Service and served in Vietnam.

Magnotta had talked about certain types of soldiers going into the jungle. They cut their hair in a certain way; looked like a Mohawk … and you knew that was a special situation, a commando kind of situation, and people gave them wide berths … we thought it was a good idea