The story begins 25 years ago with the opening of the Hong Kong Victoria Harbour tunnel by business partners Paul Wagner and Nigel Griffith (Alan Scarfe). Paul attends with his twin baby sons, Chad and Alex. However, after the celebrations, the family is followed home by a Triad hit squad on orders from Griffith and crime lord Raymond Zhang (Philip Chan). A shootout ensues, in which Paul and his wife are killed by the bodyguard Moon (Bolo Yeung). Chad is rescued by the family bodyguard, Frank Avery (Geoffrey Lewis), and raised abroad. Alex is dropped off on the doorstep of a Hong Kong orphanage.
Those 25 years later Chad (Van Damme) and Frank run a successful martial arts business, and Frank reveals to Chad that he has a twin brother. Alex (Van Damme) turns out to be a streetwise punk in the Hong Kong criminal world. When finally meeting Alex, they get off on a rocky start. But there is no time for them to bicker as they have to fight Zhang and Griffith gang to get their revenge and claim the tunnel as theirs.
This film provides examples of:
- Amazonian Beauty: Kara, who is played by a world-class bodybuilder.
- Attempted Rape: One of Griffith's mooks tries to have his way with Danielle but Alex arrives Just in Time to prevent it from happening.
- Bottomless Magazines: There are several abuses of this throughout, but by far the most glaring is during the warehouse scene about halfway through. Alex dual wields a pair of Beretta 92FS (which hold 15 rounds, plus one in the chamber), and during a protracted shootout, clearly fires in excess of 30 or more rounds from each gun without stopping to reload.
- The Cameo: Second unit director and stunt coordinator Andy Armstrong plays Chad and Alex's father Paul.
- Co-Dragons: Moon is the dragon and Number Two for Zhang, while Kara and Pete are co-dragons to Griffith. Though all three share equal authority when both BigBads are involved.
- Dumb Muscle: Averted with Moon who is clever, crafty, and vicious.
- Alex is Billy and Chad is Jimmy with Danielle being Marian/Marion the love interest. Characterwise, Alex is closer to Jimmy, but Jimmy doesn't get the girl.
- Kara is Linda. She even wears an outfit similar to female enemies in the first game, but she does not carry a whip.
- Moon is one to Abobo and Bolo. He wields oil drums and is a Giant Mook. So this makes him an expy of an expy an exp.. Aaah!
- Peter is this to the Mysterious Warrior from Double Dragon II: The Revenge. He does not have supernatural powers or dresses like him for that matter, but he uses darkness to his advantage as this video demonstrates.
- The film as a whole is a more accurate depiction of the Double Dragon video game.
- Extremity Extremist: Peter uses nothing but kicks when fighting. It makes sense considering he's wearing spurs on his shoes for extra damage. Alex and Chad do mix it up with there moves, but the former seems to do a lot of his fighting with punches, chops, elbows, and neck breaks. The latter usually pulls of a lot of kicks and spin kicks.
- Fan Vid: The Van Damme Fan 2009 has put out a series of videos with clips of Double Impact replaced with sound effects from Double Dragon II on the NES.
- Imperial Stormtrooper Marksmanship Academy: The mooks are alright shots at the beginning when they're killing Chad and Alex's parents, but later on, when it's Van Damme they're shooting at...
- Pervy Patdown: Danielle Wilde uses her employment in Griffith's company to search for a document the twins need. She's caught by Griffith's assassin, the muscular Butch Lesbian Kara, who puts her up against a wall and suggestively frisks her. Kara suggests that Danielle frisk her, but Danielle disgustedly runs out as Kara laughs at her.
- Plot Armor: With Van Damme its a given but the biggest issue was Frank when he was held captive in the boiler room. No explanation given as to why he was spared.
- Polar Opposite Twins: Alex has grown up as a brutal gangster while Chad grew up to be a personal trainer.
- The Quiet One: Moon has about a total of three lines. One of them is in Chinese and there are no subtitles for that one line.
- Scars Are Forever: Moon as result of getting shot in the face by Frank has one underneath his right eye.
- Shout-Out: It seems the people working on this film were closet fans of the Double Dragon games. Considering this movie came out in 1991, Double Dragon was still popular at the time and arcade machines were commonly found in movie theaters and arcades.
- You Have Failed Me: Moon kills one of his men for failing to beat up Alex (though they don't know yet that it's Chad they are fighting). Also Griffith and Zhang have Kara kill one of their associates for having one of their drug labs destroyed.