Abhorrent Admirer: Simon Belmont gained a few of these for comedic effect. In the episode I Wish I Was a Wombatman a blue eyed octopus with an hourglass figure fell in love with him the moment he expressed an interest in acting. A heavy set female gorilla also fell for Simon and tried to kiss him in the episode Queen of the Apes.
Adaptation Distillation: The comics released by Valiant Comics were altogether better-written (though that isn't saying much) and spent quite some time exploring the relationships between the characters instead of the show's simplistic "game world of the week" plotlines. They couldn't use half the N-team due to legal issues, but this was a blessing in disguise, as it was the far more annoying and less true-to-source-material half. And they actually remembered that Metroid has a heroine, and other characters besides Mother Brain!
Audio Erotica: In the episode Mega Trouble for Megaland, Medusa seduces Simon with her sexy voice alone to the point where he is ready to kiss her sight unseen. Once he does see how ugly she is Simon turns to stone. Medusa effectively pulls off a subversion of Audio Erotica, a "Siren Switch."
Considering that the Captain N cartoon takes place after the original Castlevania and Medusa's floating head is the second boss in that game (even though Captain N was going with the Kid Icarus variant of Medusa it's hard to imagine that they wouldn't be the same character in this universe) and plus the fact that the Castlevania series is littered with Medusa heads he really shouldn't have fallen for this trick. Of course Simon has been shown to be quite stupid at times in this cartoon so it remains a possibility. In this universe, perhaps he didn't look at Medusa's big floating head during Castlevania, or he never faced her as the second boss since this cartoon took many liberties with the games they represented. Or once again, he was just really stupid or really turned on by her voice... Eh they really didn't do the research when they made this cartoon anyways.
Years later in Castlevania video games, the Belmonts and other Castlevania protagonists have been shown to be immune to Medusa's power to turn men into stone. Typically when they do get turned to stone they can break out of the stone casing and continue to move.
Bare Your Midriff: Princess Lana, and also the redesigned Princess Zelda in the second season.
; Kevin wishes for enhanced skills, and quickly realizes Victory Is Boring. Mega Man wishes for enhanced strength, and nearly knocks down the palace. Princess Lana immediately wishes that "no one had made any wishes", returning things to normal for the moment so they can get on with the plot.
Betty and Veronica: In the show, Kevin is the Betty to Simon's Veronica and Lana's Archie while in the comics, Lana is the Betty to Samus's Veronica to Kevin's Archie.
Brainwashed: Kevin in the very final episode. Also has elements of Brainwashed and Crazy about it as although he never directly attacks the heroes, he very well could have at the end and he did act a bit violently when "training" some of the villain's warriors.
Simon also has this happen to him twice, one time literally via Eggplant Wizard and King Hippo.
Another episode revolved around a hypnotic ink Mother Brain devised, that did this to anyone who read the words printed with it.
Black Sheep: Lana's introverted brother, Prince Lyle, is a boxy kind of guy who lives in the Tetris portion of Videoland. He shows up in one episode, then briefly again in the third season to provide a Deus ex Machina.
Broken Pedestal: In one episode Kid Icarus gets to meet Wombatman, the star of his favorite show. His disillusionment when he realizes Wombatman is just an actor is painful.
Clip Show: "When Mother Brain Rules", which is missing from the DVD sets.
A clip show in the purest sense of the term, this episode has no new footage whatsoever, and no framing story to justify the clips. Even stranger, all the voices were missing in the clips, so it was half an hour of voiceless recycled animation with background music (and very occasional out-of-nowhere narration from Simon.) Needless to say, little kids watching it in 1991 were pretty damn confused.
When the episode aired in syndication, the voices were put back in.
This was actually deliberately done so the cast would be forced to say the name of Pit's video game as much as possible, thus increasing brand awareness. Luckily they didn't stoop as low as to rename Simon "Castlevania."
Mother Brain is the evil ruler of planet Metroid. Actual Metroids only show up briefly in the comic.
Disappeared Dad: Lana's father, King Charles, is apparently trapped in some kind of alternate dimension. He shows up in one episode.
Disintegrator Ray: Kevin's Zapper, in the comics. In the cartoon, literally anything from a tactical nuke to a mosquito bite.
The Dog Bites Back: King Hippo and Eggplant Wizard are prone to do this if Mother Brain slaps them around too much, by turning on her with whatever Macguffin they were sent to retrieve. Of course, this never sticks, yet for some reason, she continues to keep them around...
The Drag Along: Simon F'ing Belmont. Quite a turnaround from the guy that risked his life against the legions of darkness by himself, eh?
Evil Former Friend: Mike Vincent in "The Most Dangerous Game Master". The villains didn't know they used to be friends when they created an evil android based on Kevin's memories of him, so Kevin is able to make him do a Heel Face Turn by reminding him of when they were friends.
Genre Savvy: One of Kevin's greatest advantages was that he had played all of these games and knew all of the shortcuts, enemy weaknesses and strategies.
Even if it's something he couldn't possibly know from playing Nintendo games, like where warp zones between disparate games are.
Kevin even seems to know everything about games released after he entered Video Land.
This article discusses the changes in-depth (mostly for the featured Mega Man characters) and suggests that the creators had poor reference material. Still...
One of Mother Brain's early plans was to research the real world Kevin and find a game he wasn't good at, thus removing Captain N's Genre Savvy. She finds that Kevin can't beat The Adventures of Bayou Billy, and sends him to its Videoland counterpart, Bayou Land. It almost worked, until Bayou Billy showed up.
Getting Crap Past the Radar: In the first episode where King Hippo and the Eggplant Wizard kidnap Princess Lana in her room, Hippo (poorly) impersonates her as Kevin knocks on her door, saying that "she's not decent", with the Wizard responding with "You can say that again". Considering the size of Hippo's boobs and nipples...
In the comics Samus Aran almost goes ahead with some pretty questionable stuff to win Captain N's affections. In one issue where she and Princess Lana are in jail, she almost leaves Lana there when escaping. In another she ends up in the Bad Future and rejoices that Lana is gone and she can have Kevin all to herself, despite the fact that, you know, the bad guys have taken over every world except the garbage planet where Kevin now lives, and by not going back in time and changing one thing she's screwing over everyone in Videoland. She does go back in the end.
Merchandise Driven: Somehow, Captain N and the N-Team always seemed to end up in the world of the hot new game that Nintendo or one of its licensees was trying to promote. Which is probably the only reason stuff like Bayou Billy ever made it on the show.
The aforementioned Clip Show episode for the aforementioned reason.
"How's Bayou", well, sorta... There were two versions of the episode. The original was never completed, due to time constraints, but when the series was picked up for syndication, a second, more common version was shown with additional scenes and dialogue to keep the storyline in place, but with other dialogue taken out as well. Only the original was included on the DVD set, and the more common syndicated version is nowhere to be found in that set.
In one episode, the Eggplant Wizard (disguised as a TV repairman) even used a mushroom to transform into a giant escape pod so he and King Hippo (also disguised) can escape from the Palace of Power after figuring out Kevin's greatest fear.
Nintendo Hard: Referenced on the show, as even though Kevin is the ultimate gamer and he knows every secret and strategy to nearly every NES game ever made, even he can't get very far in The Adventures of Bayou Billy.
Off Model: Not that the series' animation quality was good per say, but there are plenty of notable examples. Including the entirety of "How's Bayou" and the aforementioned change in art style in season three.
Plot-Driven Breakdown: At pretty much any point Kevin could shoot and kill Mother Brain and thus end her reign of terror, expect his blaster or his controller to break down and render him helpless. It didn't happen that often, but the plot reasons are transparent.
He actually does blast her in the first episode, but they know she'll return - which is in itself a plot breakdown.
Rule of Funny: While certain characters such as Simon Belmont could have been depicted a bit more seriously and accurately (considering on how the Castlevanias were pretty tame at the time). However the show like many other animated shows at the time was a very light-hearted comedic series and Di C wrote certain characters such as Simon Belmont as they did just for the sake of comedy.
Shoddy Knockoff Product: The show is basically a goofy remake of TRON with Nintendo characters. Mother Brain is essentially a comedically goofy version of the Master Control Program, which is what you would expect from a villain that's a giant face inside of a computer world.
Subverted Suspicion Aesop: A very abrupt one (due to the short run time) in "Return to Castlevania." Alucard is the Count's son, wait he's saving Kevin and Simon from the Count, oh wait never mind he's not. Keep in mind this literally happens over the span of two scenes.
Title Drop: Oddly enough, the episode title in question, "Nightmare on Mother Brain's Street", is used in a line spoken by Kevin in an earlier episode.
Happy Birthday Mega Man has this spoken by the N-Team at the beginning of the episode, and ends with the Warp of Life saying it as well.
Totally Radical: Kevin's dialogue is embarrassingly littered with words like this. Also, Kevin and Lana trying to dance in 80s dance moves is particularly bad since they just look like they're having muscle spasms.
In spades and parodied (to an extent) in a later episode.
Game Boy: "Mondonose does not compute, please re-enter data"
Mega Man: "Looks like Kevin will have to teach you Californish, Gameboy".
Trapped in TV Land: Well, Videoland. Actually, Kevin is free to go home any time he wants, except he'd lose all his memories of Videoland in the process. As no time will have passed in the real world once he returns, He Chooses To Stay until the Big Bad is defeated. Think Narnia for gamers.
Training Montage: In (where else?) Videolympics. Even ends with them running up a big staircase.
Whole Plot Reference: Naturally, this being the kind of show that it is, some episodes will reference the plot of a single game wholesale; for example "Mega Trouble in Mega-Land" largely references the plot of Mega Man 1, "Quest For The Potion of Power" references Zelda II: The Adventure of Link, etc. (Other episodes, while taking place in the world of a particular game, don't necessarily have much to do with the plot of the game in question.)
Verbal Tic: Mega Man and Kid Icarus. Mega adds mega- to the beginning of a lot of words, while Kid Icarus adds -icus to the ends of words.
You Don't Look Like You: A frequent complaint for Mega Man, Kid Icarus and especially Simon (who currently takes up the page image). One-shot characters (like Pero from "Once Upon a Time Machine") can also fall into this.
Speaking of Mega Man, the Robot Masters get hit with this hard when they appear, especially Cut Man and the Robot Masters from Mega Man 2.
One of the most drastic examples is the series' version of Kraid who looks like this◊. He hardly bears any resemblance to even his original NES appearance, let alone his later, more iconic appearance from Super Metroid.