Writer and director Dito Montiel was reluctant to cast Shia LaBeouf in the role of young Dito because Montiel was intent on casting an unknown. After the first rejection, however, LaBeouf pushed for one more audition. He came into the casting office, punched a hole in the wall, and convinced Montiel that he could bring the requisite amount of anger to the role.
Shia LeBeouf and Channing Tatum only had one day to get to know each other, despite playing childhood friends. They decided to go out and get drunk on the streets of New York City. They remain good friends to this day.
The real Laurie died of A.I.D.S. before Dito Montiel returned to New York City. He decided to write her as being alive and well in the film, partially as a way of being able to see her again, saying, "I wanted to walk down those streets again and fall in love with Laurie again, it would have been nice to have had that moment at the end of the film where Dito met Laurie, reconnecting as adults."
Many of the locations used in the film were the same places where the actual events had occurred. The conversation between Dito and Flori in the early morning for example is down the street from where the real Antonio had lived. Dito Montiel joked that many of his childhood friends would hang around the set for filming, and tell the cast members "I never would have said that."
Robert Downey, Jr. had originally planned to direct the film himself. But in the four years of pre-production, he became busy with various other projects. Eventually Dito Montiel decided to direct, despite having only made a couple of short films beforehand. Robert Downey, Jr. remained on as a producer.