Darkwing's revisited by Comet Guy, a hero from the planet Mertz, who brings him back to perform a super-urgent mission. Turns out the only person on the planet with no powers has disappeared, and with no-one to rescue all the heroes on Mertz have nothing to justify their existences, so they enlist Darkwing as their new designated "rescuee".
This episode contains examples of the following tropes:
- Attack of the 50-Foot Whatever: The device that removes superpowers from heroes also works in reverse, making Ordinary Guy bigger and stronger. As he and Darkwing fight, they keep shooting themselves with it, making them bigger and bigger until they dwarf the entire planet.
- Badass Normal: The people of Mertz don't think Darkwing is an actual superhero because he doesn't have powers, despite Darkwing claiming that one doesn't need powers to be a hero. He ends up proving this to them by figuring out how to save the day, when the rest of them are left helpless after losing the powers they rely on all the time.
- Beyond the Impossible: The finale between Darkwing and Extraordinary Guy, with Artistic License – Space in full effect. The two can survive just fine in the vacuum of space, and grab hold of things like a crescent moon, stars and even the Big Dipper to use as weapons.
- Everyone Is a Super: Planet Mertz is a planet where everyone is a superhero of the Flying Brick variety.
- Face–Heel Turn: Invoked by Darkwing as he attempts to make Comet Guy into a supervillain for Mertz. It doesn't take. Ordinary Guy's does though.
- Good Old Fisticuffs: Official Guy tries to "settle things the old-fashioned way" with his fists after Ordinary Guy de-powers him. As you're probably expecting, he loses pretty badly.
- Had the Silly Thing in Reverse: When Darkwing accidentally broke Ordinary Guy's strength-sapping Ray Gun, he put it back together and ended up discovering it had a reverse setting, which he used to turn himself into Extraordinary Guy.
- Human Aliens: The inhabitants of Mertz all resemble humans instead of anthropomorphic animals, except that they have superpowers and were not born on Earth.
- Manchild: When DW finds out why Comet Guy had brought him to Mertz — to be their professional Dude in Distress — he gives the proposition a hard pass. This causes all the heroes on Mertz to suddenly start bawling and beating the ground like toddlers until he gives in.
- No Ending: The episode ends with Darkwing stuck in space with no resolution.
- Not Big Enough for the Two of Us: "Did I say town? I meant planet."
- Planet of Hats: Darkwing visits the planet Mertz, where every single person is a superhero (complete with everyone having totally unnecessary secret identities). There is only one person on the planet without super powers, whose name is actually Ordinary Guy. Everyone else spends their entire lives trying to rescue him from peril (which in practice means gigantic, city-smashing brawls over who gets to help him cross the street.) Needless to say, Ordinary Guy's life sucks. Eventually, he snaps and becomes the planet's first and only supervillain.
- Ridiculously Average Guy: Ordinary Guy is the only person in his planet without any powers whose entire job is to constantly be "rescued" by the superheroes from everything (all superheroes need to have ordinary people to save, you see). Eventually, he got so fed up with the total lack of privacy that he became a gadget-using supervillain.
- Shout-Out:
- The title is a pun on Planet of the Apes.
- The ending of King Size Canary is spoofed.
- Skewed Priorities: When Ordinary Guy used his Ray Gun's reverse setting to become bigger and stronger, Comet Guy's first comment was to complain that he didn't need saving anymore.
- Superhero Paradox: A comedic inversion. As noted a planet full of superheroes is pointless if there's no-one to rescue from danger. With all the chaos they cause fighting over the one regular person to rescue in order to justify their existence, around the middle of the episode Darkwing starts to realize introducing villains for all these heroes to fight might actually be an improvement!
- Un-Sorcerer: What made Ordinary Guy so special is that he was the only person on the planet Mertz that wasn't a superhero or had any powers. This is deconstructed in that since the planet's population was made exclusively of superheroes, Ordinary Guy was the only civilian they could exercise their heroics on. Since the society he lived in basically defined itself by labeling him as a helpless bystander that "needed rescuing", it eventually drove him to becoming a Gadgeteer Genius supervillain.
- Unwanted Assistance: The reason Ordinary Guy turned evil. The rest of the denizens of Mertz kept putting him in danger just to save him.
