Please do not read the following if you have not seen the movie. It will ruin the xperience.
Many people have been confused by the ending of this movie.
I think the ending was actually quite simple. Let me explain.
What the viewer sees: In the ending of the movie, Monty is being driven to prison, where he'll spend 7 years doing hard time. Then we jump to a sequence narrated by Monty's father. It mentions he and Monty exiting the freeway and heading out west thereby eluding the authorities and assuming a new identity, raising a family and blending into society.
The next scene returns to realtime showing Monty's face busted up and we realize that the previous scene was just a vignette showing one of Monty's options.
What actually happens Monty actually goes to prison. The previous vignette was just an explored option. A dream sequence if you will. But the fact that we return to see Monty riding with his father shows that Monty is indeed willing to stop dealing drugs, do his time, and get his life turned around. If you notice during the dream sequence, everyone is wearing white, representing Monty's American Dream where everything is pure and clean and Norman Rockwell-like. It is not a flash forward to the future, nor a flashback. Just a small image of what could be.