The script went through 8 completely different rewrites.
The script was written in 6 months.
If you look closely, you can see several green objects in the background of some scenes. This is to hint at Tommy's envy that will reveal itself towards the end.
The clothes Tommy wears throughout the film match his inner emotions. At the start, Tommy wears dark because he's in a dark place following the death of his father. During the montage when he talks on the phone, Tommy has more lighter wardrobe. Then when no one picks up his calls, Tommy wears gray because he is in a state of uncertainty and abandonment. During the flashback montage with Tommy's father, Tommy's clothes get darker and finally land on green (symbolizing envy and bitterness).