Del Shannon re-wrote and re-recorded his classic hit "Runaway" for the title sequence of the series.

John Santucci, who portrays Ray Luca's sidekick Paulie Taglia, was a real-life professional thief, who was busted on numerous occasions by series co-creator Chuck Adamson and Dennis Farina when they were Chicago cops. Many of the robberies, hijackings, and burglaries are based upon Santucci's crimes, including the museum jewelry heist profiled in the pilot, according to the DVD liner notes.

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 (1995). By the same token, Andrew "Dice" Clay's character of Max Goldman, and Robert De Niro's character of Sam "Ace" Rothstien in Casino (1995), are both based upon Spilotro's partner, Frank "Lefty" Rosenthal.

By the time season two began, Paulie Taglia had become so popular as comic relief that John Santucci, who played Paulie, finally got his name on the opening credits.

Nate Grossman (Steve Ryan), a member of Torello's Major Crimes Unit, is based upon a real detective of the same name, who worked with co-creator Chuck Adamson and Dennis Farina. In real life, Grossman was killed in the line of duty.

The theme music used for the series was an updated version of the hit song "Runaway" recorded by the original singer Del Shannon.

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.

The character of Manny Weisborn (Joseph Wiseman), Miami crime lord, and Luca's mentor, was based on Meyer Lansky. Throughout the series, Weissborn is always making references to Lansky's New York City associates, like "Lucky" Luciano, "Bugsy" Siegel, and Frank Costello.

Since this show and Miami Vice (1984) were produced by Michael Mann, both series shared the same technical advisers, directors, and crew members, and if you watch both series, both shows share the same supporting actors, actresses, and guest stars as well.

The character of burglar Frank Holman is based upon Frank Hoheimer, a famous Chicago burglar busted by Chuck Adamson. Michael Mann previously used the famed criminal as the basis for his movie Thief (1981).

The series ends with an unresolved cliffhanger.

While shooting season two on location in Las Vegas, Dennis Farina was filming Midnight Run (1988) at the same time, in which, ironically, he plays a mob boss.

The "Orbit Room" bar plays a recurring role throughout much of the first season, as the Major Crimes Unit's off-duty haunt. The real-life "Orbit Room" was a new, retro-themed bar, which opened at 3708 N. Broadway, Chicago in April 1986, shortly before filming began, and closed its doors just two years later.

Dennis Farina, Bill Smitrovich, and Stephen Lang all had supporting roles in producer Michael Mann's film Manhunter (1986).

During the first season, it is established that Lieutenant Michael Torrello served in the Army during the Korean War. In season one, episode fifteen, "Torello on Trial", we learn that he was awarded the Bronze Star and the Purple Heart.

In the episode where Ray Luca goes to the house of mob boss Dominic Tranchita, and shoots him with a silenced .22 pistol, while Tranchita's eating sausages, that incident is based upon how Chicago mob boss Sam Giancana was killed.