Nate Grossman (Steve Ryan), a member of Torello's MCU, is based upon a real detective of the same name who worked with co-creator Chuck Adamson and star Dennis Farina. In real life, Grossman was killed in the line of duty.
The character of Ray Luca (Anthony Denison) is based upon Chicago mobster Tony "The Ant" Spilotro. Spilotro also inspired Joe Pesci's character of Nicky Santoro in "Casino". By the same token, Andrew "Dice" Clay's character of Max Goldman and Robert DeNiro's character of Sam "Ace" Rothstien in "Casino" are both based upon Spilotro's partner, Frank "Lefty" Rosenthal.
When the story was first brought to producer Michael Mann, he said he thought the best way to tell the story was as a weekly series. He said he considered doing it as a feature film or a made for television movie as well.
In the episode where Ray & Paulie receive their passports it state that Ray was born in 1947 that mean he would have been only 16 when he first runs into Torello and he is already married with children.
Lt. Mike Torello: Hey you. You hurt anybody else, when this is over, I'm gonna find what you love the most and I'm gonna kill it. Your mother, your father, your dog... don't matter what it is, it's dead.
Why was this show so abruptly ended? It was one of the best crime dramas of its time and ended prematurely.
A
I think something was up, the stories were getting too real or too close to the truth (historically speaking) but someone's toes were stepped on. I asked Andrew Dice Clay once about the show and he said "it was on hiatus". Some hiatus! Maybe Michael Mann and many of the stars went on to bigger and better things, (Miami Vice) but it still seems like the show ended before its time.