Spiritual Adaptation: When they came out, the Double Dragon games were the best Fist of the North Star games you could buy. It's not a coincidence that Billy and Jimmy looked like Kenshiro and Raoh, fought punks in the post-apocalyptic 199X, and ultimately became each other's greatest enemies.
Game-Breaker: In the third NES game, both Lee brothers can stand back-to-back and do the Cyclone Spin Kick simultaneously. If done just right, you get a flashy new animation of their combined Cyclone Kicks. This "Double Cyclone Kick" does five times the damage of a single Cyclone Kick (roughly twice the damage of a throwing knife) and lets you mow down punks and bosses with relative ease. Just...make sure they both stay alive until the end.
The Flying Knee Kick and Hyper Uppercut in the second NES game are both ridiculously overpowered, although the former requires some ridiculously precise timing to pull off properly: you need to hold left or right on the d-pad and then press B and A simultaneously while your character is crouching, which only happens after landing from a jump or while your character is recovering from a fall. Once mastered though, you can mow down mooks and most bosses with relative ease.
The Elbow Attack in the original arcade game thanks to the easily duped AI. Normally the enemies in the game will be hesitant to approach you unless you turn your back on one of them, allowing you to catch them off-guard with the Elbow Attack, which has a decent range and always knocks the bad guys to the ground, regardless of who it is. In the second arcade game, the Elbow Punch's effectiveness is toned down a bit, but its still works to some extent.
Chin in general. He can and will mow down enemies in around three hits.
Good Bad Bugs: The famous trick for skipping Stage 2's boss in the NES version of DD1. Going far enough downstairs will cause Chin to be removed from the level data to save RAM, and the game counts him as being defeated once he disappears.
Good Bad Translation: The third NES game, while technically not a translation (since it uses an entirely different script from its Famicom counterpart than changes the plot), somehow manages to screw up the spelling of Billy's name as "Bimmy" in the opening of 2P Play mode, which has become something of a meme. Strangely, his name is spelled correctly in the single-player version of the opening.
Mis-blamed: The misspelling of Billy's name as "Bimmy" in the third NES game is not the result of "Blind Idiot" Translation: the game's plot was completely rewritten from its original Famicom release. It's just your average typo.
Incidentally, when Neon made a reference to this error with Bimmy and Jammy, they are referred to as "Mistranslated Mutants". This liberty was likely taken for Rule of Funny.
Moral Event Horizon: When Willy guns down Marian in the beginning of the second arcade game, he goes from being a mere kidnapper to a cold blooded murderer.
The Mansion of Terror from the NES version makes the most of its short length with the spooky BGM and, inexplicably, a huge, sinister pair of eyes in the wall that periodically open up and stare directly at the player.
The music that plays during the fight against player's own shadow doppelganger in the arcade version of the second game is very eerie and frightening. Not to mention that the doppelganger itself comes out of nowhere and no explanation is given for its existence. One can only assume or speculate that they represent the negative emotions of the Lee Brothers being unable to save Marian.
Porting Disaster: The game was ported to the Atari 2600, of all systems. It's as playable as the game could possibly be on the 2600, but a beat-'em-up with only one action button leads to very shallow, repetitive gameplay and the difficulty is off the charts.
Sequelitis: The arcade versions of the sequels. While Double Dragon II does improved upon the original, in the sense that it was actually an upgraded version of the original, but the increased difficulty, directional-based attack buttons, and recycled stage design turned many players off. Double Dragon 3 on the other hand, replaced the game engine completely (as it was farmed out to another team) and to top it off, the U.S. version made the extra characters, special moves and weapons accessible via item shops that required the player to insert actual credits into the machine.
"Seinfeld" Is Unfunny: Suffers from this quite a bit, even by beat-em-up standards. Many people who play a Double Dragon game for the first time nowadays will find it to be rather slow and tedious compared to the majority of other brawlers.
Willy in the NES version of the original game, whose gun can quickly kill you in a few shots. It doesn't help that if you get killed at any point before defeating him, you're right back to fighting the twin Abobos.
Woolseyism: The NES version of Double Dragon III underwent a complete rewrite during the English localization. Here's a comparison between the Japanese and English scripts.
Complete Monster: Koga Shuko, previously Victor Guisman, is a wealthy businessman who seeks to expand his control over New Angeles. Searching for the Double Dragon medallion to acquire its power, Koga sends his men to raid a village guarding the medallion, uncaring about the villagers' deaths. Converting Abobo into a giant, monstrous mook after he fails him, he blows up Satori Imada, and places a bounty on Billy and Jimmy Lee, seeking their other half of the medallion. Keeping his goons in suspended animation in his laboratory, he has them converted into cybernetic henchmen. Kidnapping Jimmy, he reveals that he murdered his father, and possesses him in order to kill Billy to take the other half of the medallion, threatening to kill Jimmy if he doesn't hand it over.
Designated Hero: Billy. The movie depicts him as a hot-headed, obnoxious screwup who essentially derails all of Marian's plans and only wins by sheer luck.
Especially when he arrives as a shadow being, then morphs into the ninja wraiths during the climax.
Some of the matte paintings depicting New Angeles appear unfinished as well.
Video-Game Movies Suck: The movie is a considered a textbook example of this trope, but some of the characters and plot elements from the movie were adapted into the Double Dragon fighting game for the Neo-Geo. And it had Alyssa Milano going for it, so it wasn't completely bad.
On the other hand, the Jean-Claude Van Damme film Double Impact seems to had been inspired by the games and it's an even more faithful adaptation than the official Double Dragon film. Bolo Yeung, the actor who was the inspiration of Abobo's character design (so much that one of Abobo's head swaps is even named "Bolo"), even makes an appearance as a giant henchman who throws oil drums at the heroes.
Stan Lee beating up thugs with Kung fu. Even if youre not a fan of the idea of Stan Lee in the comic its hard not to crack a smile at an image that surreal and awesome.
The Dragon Forces true form, an actual dragon that goes after criminals like its The Punisher.
Franchise Original Sin: Before the cartoon and film became known as prime examples of Narm, it was the comic that introduced many of the concepts that were so derided in those adaptations, like a supernatural source for the Lee brothers abilities, Toyetic outfits and vehicles, and a complete absence of any familiar characters and settings from the games, save a villain loosely based on the Mysterious Warrior from Double Dragon II. Of course, neither of them made Stan Lee Billy and Jimmys dad.
Anti-Climax Boss: Shadow Khan is built up to be a far bigger threat than the Shadow Warriors and when he's finally released he proves it by beating them all into submission and launching a massive attack on the Dragon Dojo. To defeat him the Dragons are forced to... have Daj sick a bunch of dogs and cats on him. Not even supernatural or mutant animals, just normal ones. What this says about the threat-level of the Shadow Warriors is up for debate.
Anvilicious: This show is not big on subtlety. Every episode ends with a short PSA that literally tells you the message of the episode.
Badass Decay: Shadow Khan's Terror Warriors take a sudden decrease in threat level the second time the Dragons face them. Justified, as their first appearance ends with the Lee Twins getting armor specifically built to fight them.
In season 1, Sickle is decently threatening to the Dragon Warriors, but in season 2 he gets Demoted to Extra with the result that the heroes start beating him easily.
Complete Monster: The Shadow Master is the leader of the Shadow Warriors, and the uncle of the Double Dragons, Billy and Jimmy Lee. Shortly after the brothers were born, the Shadow Master trapped their mother in the Abyss and abducted Jimmy, raising him to be his second-in-command, Shadow Boss. Despite promising his sister that he would never harm Jimmy, the Shadow Master callously orders him killed when Jimmy fails him, which spurs Jimmy into joining forces with the heroic Billy. Ruling the criminal underworld of Metro City with an iron fist, the Shadow Master has flooded the city's streets with drugs and weapons, enslaved most of its marginalized mutant population, and terrorized its citizens with illusions of their greatest fears and a massive beast called the Shadowmonster. The Shadow Master's other plots include hacking all of the world's banks; consuming minds to increase his own intellect; and starting a race war between mutants and humans by framing the mutants for the abduction of a little blind girl, who he then tries to kill. Any minion who displeases the Shadow Master is magically added to the Shadow Mural, a tapestry which is covered in dozens of victims, all of them frozen mid-scream.
Creator's Pet: Daj appears midway through season 2 and suddenly devours the plot.
Ear Worm: The theme song. Seriously it's annoying, but it gets stuck in your head very easily.
Growing the Beard: Surprisingly, season 2 shows a lot of signs of improvement. The animation is generally smoother, there's genuine continuity and developing plotlines, more World Building, and much more characterization and development. It almost makes you wonder if the show could've improved even more in the unmade third season.
The Scrappy: Daj, who drains screen time from the established characters, speaks with an incredibly annoying tone and accent, and has a ridiculous Story-Breaker Power that lets him basically save the day single-handed every time he appears.
Shocking Swerve: Dai Lung's former master being an actual dragon. It's foreshadowed only briefly in the episode it happens and seems to happen for no reason.
They Changed It, Now It Sucks!: Most DIC adaptations of video games, while often radical departures, at least kept the core themes and characters from the games intact. Not so with Double Dragon, which abandons even the slightest connection to the games with the introduction of the Shadow Master and the demise of Abobo and Willy. The focus on toyetic weapons and vehicles, unfamiliar villains, unfamiliar heroes, and concepts like the Code of the Dragon alienated anyone who was a fan of the original games and was hoping for something like them.
They Wasted a Perfectly Good Character: Abobo and Willy, two of the few villains actually from the games, get trapped in the Shadow Master's mural after a single episode in favor of a bunch of original characters.
They Wasted a Perfectly Good Plot: The season 1 finale reveals that Shadow Master is the Lee Twins' uncle and that he kept his sister (their mother) sealed away rather than killed. You would think this would be a big plot point or at least give Shadow Master some depth, but it's never really brought up again and the reveal does nothing to change how either the Lee Twins or Shadow Master act.