Adorkable: Milo, who personifies this to such a degree that he provides the page image for that trope. Intelligent, sweet, clumsy, scrawny, still brave... Top it off with the voice of Michael J. Fox, and you have got fangirl carnage on your hands. Kida makes mention of this... in her own, unique way.
Kida: You are a scholar are you not? Judging by your diminished physique and large forehead, you are suited for nothing else.
During the Leviathan's attack on the Ulysses, it briefly grabs the ship in its mandible claws and holds it up to its "eyes", close enough for Milo to watch them dilate. Considering that it doesn't attack or snap the Ulysses in half during this scene, it almost appears to be intently studying the ship. Is it analyzing the enemy for weaknesses, perhaps trying to determine whether it's a threat? Taunting the people on board with how easily it can destroy them? Lining up a killshot for its Wave-Motion Gun? Or is it so ancient that it genuinely has no idea what the hell it has in its claws, especially since the only other mechanical constructions it's ever seen are other Atlantean vessels like itself?
During the same sequence, the Leviathan takes an awfully long time to destroy the Ulysses, although it clearly could have obliterated the ship and everyone on board with a single tail slap. Is this a case of Plot Armor keeping the Leviathan from killing all the main characters in five seconds, or is the Leviathan sadistically toying with its defenseless prey? Or, as suggested above, is it confused about the Ulysses and trying to figure out what it is?
As the Leviathan is circling the Ulysses, it gives out two loud calls that the crew can't understand. Is this a Roar Before Beating, or was the Leviathan trying to communicate with the vessel?
Was Rourke Evil All Along or did he do a FaceHeel Turn? He knew about the crystal beforehand by reading or looking at the images in the book, but he didn't understand the ancient language so he couldn't know what the crystal was exactly, nor did he expect Atlantis to still be inhabited. Excavating valuable artifacts from long dead civilizations isn't evil, even if you're Only in It for the Money, but deciding to take it from still living people who depend on it is. Considering he only starts acting outright villainous after the crystal is revealed and he is given the chance to learn more about it, it calls into question if he was Evil All Along, or learning the truth made him realize the value of it and acted on that.
Animation Age Ghetto: A major factor in the movie's failure. It was intended to be the beginning of a new movement for Disney that involved making animated films for older audiences. However, those same audiences, especially the teenage boys to whom Atlantis was marketed, were predisposed to ignore Disney animation— not surprising considering that Disney has spent the entire previous decade making movies that were aimed first and foremost at very young children. The New '10s, however, brought the fall of the ghetto and Cult Classic status to the film, so it's proven itself as just ahead of its time.
Audience-Alienating Premise: While there are a number of reasons Atlantis underperformed at the box office, the one most commonly attributed to its failure is that it was simply "too different" from what viewers expected from Disney. And in all fairness, it was unlike anything Disney had produced since The Black Cauldron, which also attempted a more "mature" approach and subsequently bombed. The years following have been kinder to the film, however, and now it enjoys Cult Classic status among fans.
Not quite "music" in the conventional sense, but the Foley work on this film is spectacular—particularly the cracking rock sounds as the crystal-dome-covered Atlantis is covered in cooling lava.
Base-Breaking Character: Rourke. While quite a few fans regard him as a frighteningly believable antagonist who demonstrates the immorality of capitalist values and is charismatic enough to make the third act twist work, others call him an underdeveloped villain with a bland motivation clearly shoehorned in to give the movie a conflict.
"Common Knowledge": In 2019, rumors that this film was going to join the list of Disney Animated Canon films slated for live-action remakes started flying around the internet, with claims that Guillermo del Toro and Tom Holland were being considered to direct and star, respectively. These rumors were ultimately debunked by del Toro himself, but many people still believe them to be true, mostly because the idea of an Atlantis remake with del Toro at the helm is widely considered to be awesome.
Complete Monster: Commander Lyle Tiberius Rourke is a tomb-robbing mercenary (or, as he insists, "adventure capitalist") solely in the Atlantis operation for profit. The leader of the expedition sent to find Atlantis, Rourke maintains a gruff, militaristic indifference to the lives of those lost to the Leviathan and upon seeing the Heart of Atlantis, plans to confiscate it and sell it for double the money he'd receive. Knowing full well this will kill every Atlantean, when he's confronted on this Rourke threatens to shoot Princess Kida and shortly thereafter murders her father, never dropping his friendly façade. Rourke was concerned for little else but himself and the potential profit he could reap from Atlantis, to the point where he tosses Helga off a blimp to her death for a minor benefit to his escape, and was greedy enough in the end to make his entire party turn against him.
Crazy Is Cool: Gaetan Moliere. The man is completely obsessed with dirt... and it makes him incredibly useful. He's able to identify Milo as a linguist by Sherlock Scanning and tasting dirt from under Milo's fingernails.
Critical Dissonance: Has a critic score of 48% on Rotten Tomatoes as well as a surprisingly low audience score only around 51%. However, given its Cult Classic status and its constant inclusion in lists of the most underrated Disney movies and animated movies in general, its obvious the audience liked it more.
Cult Classic: As with Treasure Planet, this film is becoming one. It's one of the few movies that fans actually want to see join Disney's increasingly long list of live-action remakes, just so it get can a second shot at the box office.
Dork Age: Given its lukewarm critical reception and box office take, it was seen as an early warning sign that Disney was falling into one, and many critics pointed to it as in hindsight being the surest sign that the Disney Renaissance had effectively ended by this point. Many fans entirely disagree, and thus place it at the end of the renaissance instead, along with Lilo & Stitch and Treasure Planet for their bold and daring experimentation.
Ask any random person what they remember most about this movie. Nine times out of ten they'll answer the Leviathan even though it doesn't actually speak and only appears for about five minutes in total.
Vinny is arguably the most popular character. ESPECIALLY in the French fanbase, thanks to a brilliant dub that arguably makes his Deadpan Snark even funnier than in the original. He's also pretty beloved among Italian fans too, as in that dub he's given a southern accent to make him stick out from the other Italian-speaking characters and to be accurate to his canon bio about being born in Palermo, Sicily.
Lieutenant Helga Sinclair. Made apparent in her very first scene when the gobsmacked hero finds her waiting for him in his apartment like some sultry Femme Fatale in a hardboiled detective story. It helps that she's voiced by Claudia Christian of all people!
Even Rourke has a few fans. Yes, really. The genocidal sociopath. Admittedly, he does have the physique of a Hunk despite his age.
Ichthyologists and paleontologists in the audience had to laugh at Whitmore's aquarium, which contained coelacanths (a 65-million-year-old species that was thought long extinct until its rediscovery in 1938.) Probably meant to show, in the most obscure possible way, that Whitmire's been exploring the world long enough to find all sorts of hidden things.
Cookie shows off a map on his belly showing "all 38 states." There were 38 states from 1876 to 1889 (meaning he got the tattoo sometime between age 33 and 47.) He seems to think there are still only 38 states, but then, he's not all there.
While abandoning the main characters in Atlantis, Rourke mutters, "P. T. Barnum was right." Barnum's most famous (and probably apocryphal) saying, There's a sucker born every minute. and even people who don't know much about him understand that he was a complete grifter.
Cookie is confused when he finds a can labelled "cilantro" in his supplies at the start of the mission. Cilantro — Spanish for coriander — was called "coriander leaves" until the 1920s (it was introduced to British colonies in North America in 1670).
It had a big following in Canada. Probably due to how similar it was to Stargate.
Mexico as well. Probably because of the artistic similarites to Hell Boy.
It's Short, So It Sucks!: A few fans have noted that the film could have used a lot more running time to better establish the setting and give the characters more screen time. Official word is that Executive Meddling is at fault for this one, as the journey to Atlantis was set to take up a larger portion of the story in the original drafts.
LGBT Fanbase: The film has a lot of queer female fans due to the attractiveness of Helga, Audrey, and Kida.
Memetic Mutation: The part where Rourke lights a match in the dark and asks "Alright, who's not dead? Sound off." has become very popular for Gif users.
Moral Event Horizon: Rourke crosses it and keeps on going when he punches the elderly King of Atlantis so hard it causes internal bleeding, eventually leading to his death. Dr. Sweet drops out without hesitation when he sees this happen and while the other main crew members don't, Audrey and Vinny at least are shown to be disconcerted and repulsed.
Sweet: Rourke, this was not part of the plan! Rourke: Plan's changed, Doc. I suggest you put a bandage on that bleeding heart of yours. It doesn't suit a mercenary.
She Really Can Act: Given that Cree Summer is best known for voicing 90% of Sassy Black Woman characters in cartoons, it's quite surprising to hear her give such a wildly against type performance as Kida. Cree even lists the princess as her favourite role.
So Okay, It's Average: General consensus among external critics seems to be that it has a lot of good points, but a lot of bad ones too with each kind of balancing the other out. For cult fans, the latter don't really care.
Spiritual Adaptation: The movie is probably the closest thing we'll ever get to an American remake of 1990 anime series Nadia: The Secret of Blue Water. In fact, the similarities between both works are so strong that, according to the Nadia production team, there were calls for suing for plagiarism at one point. They only declined to do so because the Troubled Production of the anime had left its rights on the hands of another production company, as well as because they didn't believe they would win against the mighty Disney in court.
Yasuhiro Takeda: ...some years later, Disney would produce a cartoon that fans in both America and Japan would claim was practically a carbon copy of Nadia. Several people asked us if we planned to sue, but the only response we could give was, "Please take this up with NHK and Toho." Hiroyuki Yamaga: We actually tried to get NHK to pick a fight with Disney, but even the National Television Network of Japan didn't dare to mess with Disney and their lawyers. What we said to them was, this really had nothing to do with us but if it did we would definitely take them to court. Of course, it is all a lie. We actually did say that but we wouldnt actually take them to court. We would be so terrified about what they would do to them in return that we wouldn't dare.
Theiss Titillation Theory: Kida's Atlantean clothing bares much skin. Okay, so that's an Atlantean thing. Helga, on the other hand, wears some things with straps. Often, there is only one firmly on a shoulder at at time...
They Wasted a Perfectly Good Plot: The search for Atlantis had the potential to be an entire adventure movie of its own. Here however, it was all jammed into about a half hour of the film, which resulted in so many people feeling that it was rushed, and that the Ulysses submarine was wasted.
Vanilla Protagonist: Milo's not exactly a Flat Character, but he's also not very interesting either especially compared to the herd of quirky supporting characters. He's just a nice if determined nerd with a talent for linguistics who gets to go on an adventure.
Vindicated by History: The film was neither a huge financial or critical hit, and perhaps received one of the most lukewarm receptions of any Disney film at the time. Many questioned Disney on its choice to pursue an action-oriented animated film, one that was designed for an older audience in mind and resorted to the extensive use of CGI when traditional animation had begun to lose favor at Disney. However, these days it is becoming a significant cult classic with more and more viewers taking a closer look at the film's merits. Those who enjoy it tend to appreciate its comic book style animation and its many adventurous elements, while many in its supporting cast have grown to be fan favorites among some, especially Audrey, Kida and Vinny in particular.
Visual Effects of Awesome: The film has very good animation on the whole, but the animation on the Leviathan is amazing. Similarly, any scene with Kida and the Crystal is bound to have this.
In the Brazilian dub, Cookie is from Minas Gerais, a Brazilian state that is historically associated with countrysides and whose traditional cuisine is generally rich in fatty dishes. It fit the character well, at least until Cookie reveals his tattoo, and the dub still calls it a map of Minas Gerais.
In the English dub, Vinny speaks with an Italian accent. In the Italian dub, since obviously everyone speaks Italian, Vinny instead gets a southern accent.
In the Italian dub, Rourke's "P.T. Barnum was right" line was replaced with a simpler "The world of full of fools", since the reference would have been lost on Italian audiences.