These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Special mention to one scene in "The Ultimate Pollution" where, as he's fighting a tank, the Captain spews statistics about how there's enough steel in them to make 2000 plows.
Base Breaker: Even among the fanbase, the episode decrying overpopulation and saying you should only have two kids at the most did not go over well. The fact that the show's creator has more than two children only makes this worse. It's best not to bring it up as the debate on overpopulation is an extremely touchy issue even outside of this context.
Broken Base: Given the subject matter and aesops, the entire show can be a base breaker.
Captain Obvious Aesop: Given the show's reputation, is it really any surprise that it was guilty of this?
Critical Research Failure: Captain Planet is damaged by crude oil, a completely natural material, yet is also healed by lava and magma, both far more dangerous than crude oil. Strangely, Hoggish Greedly calls the crude oil he fires "toxic waste", but it's a storyboard error as he fired a thick, shiny glop at Captain Planet, just like oil, as opposed to the colorful glop the show represents as toxic waste.
A Belfast Catholic using the taunt "Fenian Prods" in the If It's Doomsday, This Must Be Belfast episode makes one question how much the writers actually know about sectarian hate in Ireland.
If Darwinia from the episode 'The Blue Car Line' is supposed to be a fictional representation of the Australian city, Darwin, then there is a hell of a lot wrong with it. For starters, two decades on from the episode's creation, Darwin still has a minuscule population of less than 150,000 people, little to no high-rise development to speak of, and - the funniest error considering the episode revolves around alternative transport - there's no trains (save for one train line that runs to Adelaide and Alice Springs).
Ear Worm: CAPTAIN PLANET, HE'S OUR HERO, GONNA TAKE POLLUTION DOWN TO ZERO.
Evil Is Sexy: Dr. Blight, at least until you see the acid burn on her face that her hair covers.
Hell, she's pretty even with the scar!
Looten Plunder, from the fact he is the most normal-looking male villain (though his clothes are considered tacky).
Growing the Beard: By seasons 5 and 6, the animation and narration become less error-prone and much more fluid and clean. To compensate, perhaps, the season six opening gets changed into a cheesy rap song.
Also, his element is fire. Fire is traditionally linked to agitated feelings, such as being hot blooded or being angry. A specific type of anger is called rage. Wheeler is from Brooklyn. So what the show is trying to say is that Joey Wheeler, from Brooklyn, has Rage.
Looten Plunder: You'll pay for this, CAPTAIN PLANET!
You go onto a forum and shout "EARTH!", then there is a good chance that the next four posts will be the other elements, followed by the rest of the summoning sequence. Whenever someone isn't intentionally going to pull a Combo Breaker, that is.
Moral Event Horizon: Zarm crosses this in every other appearance or so. Two words come to mind: Scorched Earth.
Verminous Skumm crosses this a lot of times. Two most infamous examples are "Mind Pollution" and "A Formula for Hate". In the former he was peddling mind-affecting drugs to teenagers and it resulted in death of Linka's cousin and in the latter he harassed an HIV-positive teenager and spread lies about AIDS, nearly ruining his life.
Dr. Blight is typical Mad Scientist who performs said experiments either for profit, For the Evulz, or For Science! But she crossed the line when she tries selling a nuclear bomb to the Captain Ersatz Hitler. The Planeteers even said that it was low even for her.
Narm: The infamous Fu-Manchu Hitler episode, wherein Captain Planet is defeated with just a stare.
"If It's Doomsday, This Must Be Belfast" is likely to be enjoyed by anyone from Belfast or who grew up during the troubles. Its epic failures in research, ridiculous stereotypes, bad accents and over-the-top message are a joy to behold.
Some Anvils Need to Be Dropped: The ENTIRE series can qualify as this, seeing how the environmental movement sputtered in the 80's. That said, it's ironically the times the show tackled social issues that tended to really resonate, especially on down the years. For example:
While the dialogue in "'Teers in the Hood" couldn't be taken seriously (so how can you portray gangs without Cluster F-Bomb? Bear in mind, it's a kids show), the images of Martin Luther King Jr. and other civil rights leaders is very powerful and it at least tries to show that gang violence is a serious problem and civil rights leaders fought for everyone to be equal and wouldn't stand for gang violence if they were alive today.
Also, the HIV episode "A Formula for Hate". Not even remotely subtle, and it might come off as hammy in parts, but the message that HIV patients aren't horrible monsters who brought their fate on themselves, that they won't give you AIDS just by existing, and that, despite their condition, they're still human beings who need support and love? In the early 1990s, that was an anvil that needed to be dropped hard, as there were people who were grossly misinformed about AIDS and HIV (and who, far more crucially, might pass it on to their kids if said kids weren't given another viewpoint).
Not to mention the drug-abuse episode "Mind Pollution", where Verminous Scumm hands out drugs to everyone causing them to go insane and causing Linka's cousin to jump off a window from the second story of a building (he survives his injuries, though, before eventually succumbing to his fatal overdose of Bliss), which show the possible effects certain real life drugs can have on a person.
And in the episode "If It's Doomsday, This Must Be Belfast", where it shows that long-standing conflicts do not have a clear cut good guy or bad guy, and they can't be resolved easily (or at all).
"The Deadly Glow" due to its Truth in Television status - it shows that while the radiation causes people to become sick, mentions that in small doses it can actually help fight cancer.
Squick: Sly Sludge is often pretty disgusting, as in the episode "An Inside Job", where he is seen happily smelling the fumes coming from a sewage pressure control valve while he tries to drown the Planeteers in waste. In "Kwame's Crisis", Sly even buries an entire town in garbage. Because the citizens of the town have lost all hope for trying to even be clean, they simply throw their trash wherever they wish, so in one scene, we get to see a woman open up a baby's diaper and toss it away, visibly showing the urine inside. "Old Ma River" also had no problems showing characters going through areas full of raw sewage, nor did it have any problems with depicting emaciated equine corpses, one of which was a vulture-covered cow carcass floating around in the Ganges River. Linka ends up getting battered by the cow's corpse, making her, Kwame, Gi and Ma-Ti sick, when they save her.
What Do You Mean, It's for Kids?: Some episodes do deal with issues that aren't about the environment, like drugs (Linka and her cousin getting addicted to drugs and Linka's cousin killing himself by jumping out of a window), HIV (the infamous episode about a basketball player's life being ruined when rumors spread that he has HIV), and racial violence (the episode about "The Troubles", the one where the Planeteers try to stop a gang war, and the episode where they go back in time to Nazi Germany). Those are remembered more than the others, either because they were campy as hell or because viewers were amazed and shocked that a kids' TV show can show such adult issues.
However, the team did use child psychologists to review the script on the most controversial episodes.