A very rare workprint of the movie is available amongst fans. Although most copies are in poor quality, it has approximately 30 to 40 minutes of footage not available in any other version. It also has all of the X-rated material removed from the final release.
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.
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.
At one point during filming Sylvester Stallone complained to cinematographer Ric Waite that they were falling behind and that he and his crew needed to work harder. Waite responded by saying that maybe if Stallone "gets his hands off Brigitte Nielsen 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 tone down his ego but after a few weeks he returned to his old egotistical behavior. In the same interview where he mentioned this, Waite also said that despite his huge ego Stallone had a great sense of humor. He also confirmed a rumor that Stallone was the true director of the film, calling credited director George P. Cosmatos a good producer, but a bad director.
Although it was considered a box-office disappointment at the time, especially compared to Rambo: First Blood Part II (1985), and Rocky IV (1985), Cobra (1986) grossed 12,653,032 dollars on its opening weekend, which was the largest opening weekend in the history of Warner Brothers and The Cannon Group up to that point. It also earned over 160 million dollars worldwide, making a substantial profit on its budget of 25 million dollars (along with marketing costs). One factor that made people think the film was less successful than it was is that the aforementioned opening weekend was the 2nd best for any film in 1986 (trailing only that for "Stark Trek IV: The Voyage Home") but Cobra finished as the 15th-highest earning film of the year; it also got lumped together with the similar huge opening/average overall returns view of "Poltergeist II: The Other Side" because both films opened wide on May 23, 1986.
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.
Some of the cuts made to avoid an X-rating include: the first murder victim having her hands severed; an extended autopsy scene, including lingering shots of naked and mutilated bodies; a longer death for Ingrid's photographer Dan, including a shot of him slipping on his own blood while trying to escape; more deaths of the townspeople during the climax, including a person getting hit in the face with an ax.
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 Confetti has a matchstick in his mouth.
The original rough cut was over two hours long. Due to concerns it might not be a hit, the final cut was 87 minutes, thereby increasing the number of screenings per day. Some of the more violent scenes were also cut to avoid an X-rating. A great deal of plot detail was either removed or sped up while most of the violence and nearly every death was edited or depicted off-screen, resulting in numerous continuity errors.
The movie was based on a novel "Fair Game" by Paula Gosling. In 1995, William Baldwin and Cindy Crawford made Fair Game, 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's case it was due to the test audience disliking the original cut.
After Top Gun (1986) became a massive box-office hit, Stallone, Warner Brothers, and The Cannon Group were afraid that Cobra wouldn't be successful, so they cut it down heavily in order to have more theatrical screenings per day. A similar thing happened with Another 48 Hrs. (1990) which was heavily re-edited to compete with Total Recall (1990), but as with Cobra, it created many plot holes.
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, "You could have been good if you had listened to me."
First draft of Sylvester Stallone's script had lot of differences from later drafts and the film. These include opening shootout taking place in movie theater instead of a grocery store and lot more people getting killed, Cobra mentioning how some psychopath he was trying to catch killed his girlfriend, additional big action sequence taking place during night on a boat where Cobra and Ingrid are hiding when they get attacked by Nightslasher's cult members but Cobra and Gonzalez manage to kill them all, and different ending in which it's revealed that Monte was actual leader of the New Order cult and when he tries to kill Ingrid he gets shot and killed by Cobra.
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 first cut of the movie featured a different, less dialogue-heavy version of Nightslasher and Cobretti's final confrontation. Cobretti originally appeared after Nightslasher screams "We are the future!" and reprised his "You're the disease, and I'm the cure" line from the opening supermarket scene. Cobra attempts to shoot Nightstalker but is jumped by Stalk, only to be accidentally shot by Nightslasher. This would have led into the hand-to-hand fight seen in the final version.
Originally, the motorcycle chase scene in the ending was to be filmed in Seattle during 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.
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 per minute, and has various accessories that were offered, such as a silencer, various capacity magazines, and a laser pointing device.
Sylvester Stallone was a fan of John Cafferty and The Beaver Brown Band and approached them about doing a song for the film. The song "Voice of America's Sons" was written for the film, and John Cafferty had contributed to the Rocky IV soundtrack as well.
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 caliber ACP. The 9mm versions were made especially for the film.
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.
Andrew Robinson and Reni Santoni also appeared in Dirty Harry (1971). In both films, Santoni plays a police officer named Gonzales, while in the earlier film Robinson (credited as Andy Robinson) played the main antagonist.
Much of Nightslasher's attack on Ingrid in the hospital scene was cut for pacing and content. The deaths of the janitor and nurse were originally shown onscreen, and Nightslasher was also meant to kill the police officer guarding Ingrid. Two later scenes - Cobretti and Gonzales taking Ingrid out of the hospital, and Cobretti talking with Monte - originally included mentions of the officer's death. These were cut to avoid continuity errors, but as a result the editing in both scenes is choppy.
In the original rough cut 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 crash into the boat first, and Cobra fails to stop his car and crashes into them. The shot of Nightslasher's car and him sighing in relief was re-purposed from an earlier part of the chase 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.
Santiago Segura has claimed that this movie was the inspiration for his well-known character Jose Luis Torrente, main star of Torrente, el brazo tonto de la ley (1998) and sequels, that he conceived as a parody of the 80s action movies. In fact, the title is a spoof of Stallone's movie, since then in Spain Cobra was titled as "Cobra, el brazo fuerte de la ley" (Cobra, the strong arm of the law).
The movie is filled with over-the-top 1980s product placement. 1. Pepsi machine and Coors display and can in first shoot-out. 2. Giant Pepsi sign beside Stallone's apartment. 3. Toys R Us commercial which Stallone watches on television. 4. Pepsi sign lit up at night outside Stallone's apartment - background for fight scene. 5. Coors California sign in store window. 6. Coca-Cola machine outside store with character drinking can of Coke. 7. Bar scene with Miller High-Life sign in background.
In 2017, Sylvester Stallone used his Instagram page to post a picture of Cobretti standing next to the 1950 Mercury car with the caption, "Comeback or throwback?" Thousands of fans used this as the opportunity to lobby Stallone for a sequel or director's cut Blu-ray of the film.
On an episode of the TV show "Brookyn Nine-Nine", Det. Jake Peralta (Andy Samberg) is driving to an undercover operation when he puts a toothpick in his mouth. When his partner says he looks ridiculous, Peralta happily says that he looks like Sylvester Stallone's character in this movie.
The trivia item below may give away important plot points.
Incorrectly regarded as a goof: When Cabretti spins his pistol cowboy-style in the supermarket, it's incorrectly regarded as a goof that the semi-automatic would have fired when twirled. The Colt National Match pistol he carried has a trigger weight of 3.5 lbs - 5.5 lbs, so while it's possible if enough pressure was applied to the trigger it would have caused an unintended discharge, but it's unlikely. Regardless, it's unwise and irresponsible to play with firearms.