Tom Selleck and John Travolta were also offered the roles of Hughes and Costanzo. Selleck turned it down due to commitments to Magnum, P.I. (1980) while Travolta's, at the time agent, Michael Ovitz, felt that the project was wrong for him.
A sequel titled "Still Running" was planned and different scripts were written. But Billy Crystal and Gregory Hines did not think any of them were strong enough to warrant a sequel and turned them all down.
On the television series "The Directors", Peter Hyams stated that when MGM offered him the project following the success of 2010: The Year We Make Contact (1984), the script focused on two old New York City cops who want to retire. Hyams suggested his idea of two young Chicago cops who don't retire and MGM agreed.
A spin-off music video was produced for Michael McDonald's hit single 'Sweet Freedom', which was a major part of the film's soundtrack. In the video, Ray and Danny are in their squad car looking at a postcard from 'McDonald' in Florida which says 'Wish You Were Here' (implying that was the inspiration for them choosing that as their holiday destination). We then see a montage of action scenes from the film over the song's intro, followed by Michael McDonald singing the song at his keyboard in a Florida bar. At the song's climax, Ray and Danny join up with him and have some beers, and then dance along to and join in the song's backing vocals as it draws to a close.
Gary Devore, the screen writer for this movie, disappeared in June 1997, while driving at night from Santa Fe, New Mexico to Santa Barbara, California, prompting an extensive search and media speculation. His disappearance was featured on Unsolved Mysteries. A year later, he and his car were discovered submerged below a bridge over the California Aqueduct near Palmdale, California off Highway 14. Devore was driving back from Marsha Mason's home where he was reportedly collaborating on a new screenplay. It is believed that Devore may have fallen asleep and went off the road and drove into the aqueduct
When Hughes and Constanza are discussing living in Florida, they observe, in disparaging tones, that the only baseball there is during Spring training. However, five years later, Florida was awarded its first team--the Miami Marlins.
The trivia item below may give away important plot points.
A plot device is borrowed from The Black Windmill (1974). In one film Michael Caine's son is kidnapped and to get the ransom (uncut diamonds) he impersonates his boss (Donald Pleasence) on the phone and gives himself permission to take the diamonds from work (MI5). In the other Billy Crystal's ex-wife is kidnapped and he impersonates his boss (Dan Hedaya) on the telephone to give himself permission to take the ransom (cocaine held as evidence) from work (Chicago police department).