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.
Accidental Innuendo: The show is full of them. Seriously, if you watch the series on YouTube and read the comments, half of them are about something involving sex.
"Now I'm on top!!!"
Abusive Parents: Kimba/Leo in the sequel series, at least where Rune is concerned. Leo pushes him hard and routinely shames his efforts — eventually abandoning him in the cliffs far from home and forcing him to make it back himself.
Big Lipped Alligator Moment: For the voice actors anyway. Knowing absolutely nothing of how the original story was supposed to evolve, a woolly mammoth coming out of nowhere sort of threw them for a loop.
Broken Base: So, is the 1989 series unnecessary and destroys everything the original series stood for, or is more realistic and better than the original series?
The main similarities are the character designs and setting - the story of The Lion King is more about accepting responsibility - Kimba is more about using authority wisely, and Kimba also deals with greedy or unaware humans messing things up for the animals.
To be fair, the "accepting responsibility" angle was imposed on the film relatively late in pre-production via Executive Meddling, and (in some versions of Kimba/Jungle Emperor) Kimba's son Rune had a similar character arc complete with a self-imposed exile ending in Rune also returning to inherit his kingdom upon his father's death and seeing an apparition of his father in the clouds. And if you take the first part of Kimba, include that element as well as removing the humans to focus entirely on the Rightful King Returns part of the plot; do the necessary changes that compressing it into a 88 min. movie would require (like merging the flamboyant, ex-Nazi, father-killing Hamegg/Viper, who sent the main character into exile and was defeated and forgiven by him just to end up mauled by another villain, with the dark-furred, black-maned, tyrannical usurper Bubu/Claw, who has a group of Hyena comic-relief henchmen and a scar over his left eye, into Scar, and giving Kenichi/Roger and his uncle's roles to the comedic animal sidekicks, creating Timon and Pumbaa) and what you'd end with would be pretty close to the Lion King.
Viewer Gender Confusion: Happened to those who're not familiar with the series watching a filler episode from the 90s dub for the first time.
The Woobie: Leo in the 2009 special embodies this trope. He hasn't yet learned to hunt properly, and even the *prey* laughs at his pathetic attempts. Considering the original Kimba/Leo swam the seas to get back home and learned early on to get tough, this cute-but-less-confident Leo comes as a bit of a surprise to fans.
Woolseyism: The dub actors weren't given the episodes in order and were forced to write their own scripts. While this brought up some issues later on involving Kimba's past, they really tried to make the best possible show they could.
Unfortunately, the 90's redub wasn't so lucky. It's worth noting that the original 60's dub sells for about $110 in boxset form, while the 90's redub is a staple in most dollar stores.
While fans will admit the 90's redub sticks closer to the Japanese Script generally, they disliked that the dub removed the original background music and non-dubbed voices. There's also a feeling that the original dub cast overall gave a better performance of the characters and that despite some confusion and censorship still retains much of the intended spirit of the show.