The custom 1950 Mercury driven by Cobretti in the film was a car actually owned by star Sylvester Stallone. The studio produced stunt doubles of the car for use in some of the action sequences, such as the jump from the second floor of the parking garage.
When Sylvester Stallone was signed to play the lead in Beverly Hills Cop, he did a lot of work on the screenplay, turning it into an action extravaganza that the studio couldn't afford. He eventually left Beverly Hills Cop and channeled his ideas for that project into this movie.
The submachine gun used by Marion Cobretti in the final showdown with biker gang is a Jati-Matic. The Jati-Matic first appeared in the early 1980s, but was never adopted by any country for use. It re-appeared in Finland in the mid-1990s as the GG-95 Personal Defense Weapon made by the Golden Gun Company. The gun is chambered in 9x19 parabellum, has a cyclic rate of 600 rounds/min, and has various accessories that were offered such as a silencer, various capacity magazines, and a laser pointing device.
Andrew Robinson (Det. Monte) and Reni Santori (Sgt. Gonzales) had worked together 15 years before in another cop film, Dirty Harry. In that one, Robinson was credited as Andy Robinson, who played the psychopathic 'Scorpio'.
Much of David Rasche's role was cut from the final version. In the behind-the-scenes documentary, an additional scene featuring him is shown being filmed.
In the diner scene where Cobretti brings over the fake hamburger to Ingrid, there is an oval frame on the wall that says "King Cobra" - a brand of beer.
Cobretti uses a custom Colt Gold Cup National Match 1911 in 9mm using Glaser Safety Slugs, a frangible bullet. This is shown when he unloads his pistol in his apartment to clean it. The Colt Gold Cup National Match 1911 is usually chambered in .45 ACP, the 9mm versions were made especially for the film.
Although it's looked back on as a flop, Cobra grossed $12,653,032 on its opening weekend, which was the largest opening weekend in the history of Warner Brothers up to that point.
The Paula Gosling novel 'Fair Game' on which "Cobra" is based is also called 'A Running Duck'. When the movie came out Sylvester Stallone allegedly wanted the novel reissued with himself credited as the author. Ms. Gosling declined the offer.