Most 80s action heroes were called John (John Rambo, John Matrix, John McClane etc.). However, in this movie the hero is named Marion, which is the real first name of the epitome of the cinematic tough-guy - John Wayne.
When Sylvester Stallone was signed to play the lead in Beverly Hills Cop (1984), 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.
A very rare workprint of the movie is available amongst fans. Although most of the copies of it are in poor quality,it has approximately 30 or 40 minutes of extra scenes which are not available in any other version. It also has all of the X rated material removed from the released version.
Director Nicolas Winding Refn is a huge fan of Cobra. In Refn's cult movie Drive (2011), the main character has a toothpick in his mouth in some scenes. This is Refn's homage to the opening scene of Cobra where Cobra has a matchstick in his mouth.
One time during filming, Sylvester Stallone complained to cinematographer Ric Waite that they are falling behind and that he should push his crew to work more and harder. Waite's answer on Stallone's order was quite surprising. He basically told Stallone that if he stops "playing around" on set with Brigitte Nielsen, gets his hands off her ass and stops showing off to his bodyguards, maybe they wouldn't have problems with time. Although Stallone was shocked that somebody would talk to him that way, he did behave for about three weeks and then returned to his old ego fuelled behaviour. Waite said in an interview that despite his huge ego Stallone had a great sense of humour and he also confirmed a famous rumour that Stallone was actually the one who was giving orders during filming and that he was the one who directed Cobra behind the scenes, because, in Waite's words, credited director of the movie George P. Cosmatos was a good producer, but a bad director.
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.
The movie was based on a novel "Fair Game" by Paula Gosling. In 1995 William Baldwin and Cindy Crawford made Fair Game (1995), which was also based on the same novel by Gosling. Just like Cobra, Fair Game was also re-edited by Warner Bros. in post production, but in Fair Game case it was due to the test audience disliking original cut.
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.
Original rough cut of the movie was over 2 hours long. Due to the concern that it wouldn't be a hit,it was cut down to 84 minutes. Some of the deleted material was cut because of the MPAA,who originally gave the movie an X rating due to the graphic violence. After massive re-editing a great deal of plot was either removed or speed up while most of the violence and nearly every death scene is edited or is always happening offscreen, often causing continuity mistakes. Because of the re-editing a great deal of action scenes are also cut.
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.
Some of the MPAA cuts that were made for R rating include murder victim having her hands severed, more shots of dead bodies in autopsy scene including lingering shots of naked and mutilated body of murdered women, longer death of Ingrid's photographer Dan and part where he slips on his own blood and falls on ground, more deaths of town's people during the climax of the movie including a scene where one person is hit with ax in the face.
The main reason the film suffered heavy re-editing before its theatrical release was because after Top Gun (1986) became a massive box office hit Stallone and Warner Brothers studios were afraid that Cobra wouldn't be successful so they cut it down in order to have more theatrical screenings during the day. A similar thing happened with Another 48 Hrs. (1990) which was also heavily re-edited before theatrical release so that it could compete with Total Recall (1990), but just like with Cobra, re-editing caused many plot holes in the movie.
In the first cut of the movie there was a slightly different version of confrontation scene between Nightslasher and Cobretti. Instead of the more intense version that was ultimately used with more dialogue between Cobretti and Nightslasher, in the earlier version Cobretti shows up right after Nightslasher screams "We are the future" and with a relaxed, almost smiling, look on his face he repeats the same line he said in the opening grocery store shootout scene "You're the disease, and i'm the cure". Instead of saying the entire dialogue how murder is against the law and that Cobretti is gonna have to arrest him if he can, Nightslasher simply looks at Cobra with a surprised/shocked look on his face and right when Cobra is about to shoot him Stalk appears and jumps on Cobra only to get shot by Nightslasher. There is a noticeable continuity mistake in the final version of the scene though; when Stalk jumps on Cobra there is a fire behind him but in all previous shots of him holding the Nightslasher at gunpoint and saying his dialogue there is no fire behind him. That's because this scene was re-shot at different location.
Brian Thompson auditioned seven times for his role before he was hired. On his fourth audition he met Sylvester Stallone and both he and the director thought that Thompson was too nice to play the role of Nightslasher. But after a screen test he immediately got the job. Thompson repeatedly asked Stallone about his character Nightslasher, like how Stallone would want Thompson to play him, character's background, his reasons for doing what he's doing... but Stallone wasn't interested in explaining Thompson's character and he basically told him that he is evil because he is evil. In an unfortunate surprise for Thompson, when filming of the movie was finished, director George P. Cosmatos told Thompson for no reason - " You could have been good if you have listened to me."
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'.
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.
The official soundtrack release includes a track called "Skyline" which is not heard anywhere in the movie. This is because scenes in which this track was used were cut out from the movie during re-editing. Originally there was a scene in which Cobretti is sitting in his home, looking at a sunset (there is a similar scene in the beginning of theatrical version in which he is cleaning up his gun and then looks at streets outside of his house) and soon, right after Nightslasher and his gang members killed the second victim and cops show up at the scene, Cobretti gets the call from his police chief or somebody else to go and meet with them and it is in this scene where the "Skyline" track is heard. "Skyline" was also originally used in some other scenes including the ending but from some reason it was removed and replaced with the song "Voice Of America's Sons" by John Cafferty.
When The Nightslasher says his long monologue, right before his fight with Cobra, Brian Thompson had to do the scene with the script girl because Sylvester Stallone was watching the basketball game on TV.
In the original rough cut of the movie the car chase scene between Cobra and Nightslasher was longer and ended differently. While in the theatrical version Nightslasher shoots at Cobra's car and causes him to crash into the boat, in the original version Nightslasher and his driver are the ones who crash into the boat first and then Cobra fails to stop his car and crashes into them. The shot of Nightslasher's car and him sighing in relief after Cobra crashes his car was edited from an earlier part of the chase (which for same reason was not included in final cut) and the shot of Cobra seeing the boat before he crashes into it was actually taken from Nightslasher's car crash. However if you watch the theatrical version of this scene closely you can still see Nightslasher's crashed car right when Cobra's car crashes into the boat.
Originally, the motorcycle chase scene in the ending was to be filmed in Seattle dueing the night on a ferry between the islands. Even though everything was prepared to start filming the scene at night, Sylvester Stallone ordered for the ending to be changed and to happen during the day because of the mosquito problem at that time which would have made night-time filming very difficult to endure.
In an earlier version of the script it is revealed that Monte is actually the head of the Nightslashers. When Cobra finds out he shoots Monte in the head with his sub-machine gun. This ending was rewritten, and the Monte character was just turned into a pencil-pushing bureaucrat.
Much of the hospital scene in which Nightslasher tries to kill Ingrid was cut down for pacing and because of the violence. The death scenes of the janitor and nurse were originally shown onscreen and there was also an additional murder scene where Nightslasher kills the police officer who was guarding Ingrid. In later scenes (where Cobretti and Gonzales are taking Ingrid out of the hospital and when Cobretti talks with Monte) the officer's death was mentioned. This was cut to avoid continuity a mistake leading to some bad editing in that scene.