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 Aesop: It was Hal Sparks in the "I Love the 80's 3-D" VH1 special who put it best:
"And the lovely little moral of this story is: Girls, give up your voice so you can have legs that you can spread for your man. ...What!?"
Alternative Character Interpretation: Ariel's main motivation for becoming a human. While both her interests in human culture and Eric are reasons why she became a human, it's a matter of debate as to which one was the bigger motivation for her.
Badass Decay: Eric and Triton in both the sequel and musical.
Also, the Evil Manta in his fourth/final appearance in the TV show.
Sebastian was so popular that voice actor Samuel E. Wright recorded two albums as the character. There was even a tie-in Disney Channel special, and the character also starred in his own shorts on the short-lived Saturday Morning CartoonRaw Toonage, along with his nemesis Louis.
"Vanessa" (Ursula's disguised form) is really popular with some fans.
Undertow from the sequel. With Melody being a copy of her mother, Morgana and her sting rays being copies of Ursula, Flotsam, and Jetsam, and Tip and Dash being copies of...Timon and Pumbaa, Undertow is the only new character with some originality. Doesn't hurt that he's voiced by Clancy Brown.
Benjamin from the prequel. While the movie doesn't sit too well with the fans most agree that he is its saving grace, being an Ambiguously Gay and yet still very cute manatee.
Epileptic Trees: In The Da Vinci Code, author Dan Brown puts forth the theory that the directors and animators were pagan goddess worshipers and scattered clues and obscure references to the "Sacred Feminine" throughout the film, including Ariel's red hair. The reality is far less mystical though: the animators chose to make Ariel a redhead to avoid comparisons with Daryl Hannah's blonde mermaid character from Splash, and also because it gave a nice contrast with the blue sea and her green tail.
Evil Is Sexy: Ursula in her Vanessa status. Some viewers found Ursula sexy even in her original form. "Don't underestimate the importance of BODY LANGUAGE!".
Fair for Its Day: Today this movie is considered by some to be rather cringe-worthy, as its heroine is a girl who abandons her family and her home for a guy she hardly knows. At the time though, Ariel was written by Disney to be a proactive girl, following after the more passive and demure Snow White, Cinderella, and Aurora. She also was the first Disney princess to set out and win the heart of the guy she loved, rather than have him show up and carry her off. (And she was also the first Disney princess to save the life of her prince, twice.)
The original VHS cover...oh, the grief that one (just one) of the coral spires on Triton's castle caused...
Ariel gasping for breath once reaching the surface after being changed into a human is very orgasmic-looking
"Funny Aneurysm" Moment/Harsher in Hindsight: In-universe example: In the episode "Metal Fish", Ariel saves Hans Christian Andersen, and it is heavily implied that he ended up writing the story in honor of her saving him. Said story ended up published a year later in the story, and given what happened to the character based on her, it's unlikely that Andersen was too happy that Ariel married Eric.
Also either this or "Funny Aneurysm" Moment, but Ariel (and by proxy, Vanessa), was originally potentially going to be voiced by Melissa Fahn. Given who she later acted as a dub voice for, the fact that she later plays a woman who actually attempts to sabotage a relationship between the main character and her lover through very similar methods to what Vanessa did to Ariel is somewhat of an eyeopener.
In the original Hans Christen Andersen book, the mermaid had to earn an immortal soul at the end where she previously had none, and nowadays it is often joked that gingers have no soul. Consider Ariel's hair color in the Disney adaptation.
Vanessa, a villainous split personality of Ursula, is voiced by Jodi Benson. In the English dub of Grandia II, Jodi Benson voices Millenia, a villainous split personality.
Ariel was modelled after actress Alyssa Milano. Years later, Milano's character on Charmed would be turned into a mermaid - in a plot that heavily references this film. To make it even more hilarious, Milano is terrified of water (and shooting the underwater scenes were very tricky for her).
Magnificent Bastard: The Evil Manta from the series, who manages to turn the different species of the entire kingdom against each other in his debut episode. Not only that, he also tricked Ariel into setting him free to begin with. Oh, and he's voiced by Tim Curry, no less. Though his fourth and final appearance puts him through Badass and Villain Decay; suddenly he's a father, Tim Curry voices him a lot less creepily, and he ends up with some redeeming qualities.
Ursula in the movie is also a contender for how she seems to be ahead of the game virtually before the game (the plot) has even begun!
Moral Event Horizon: Ursula starts well over the line and really crosses when she interferes with her own deal with Ariel and hypnotizes Eric into falling in love with her in disguise. It gets worse when she attempts to blast Ariel with the trident, after turning into a giant version of herself. Also in the TV series, she attempts to murder an alleged bad-luck creature despite it being completely harmless to begin with.
King Triton crosses this when he destroys Ariel's collection of human knick-knacks. It doesn't matter if he feels remorse for it, because this (and a little persuasion from Flotsam and Jetsam) is what prompted her to make the infamous deal with Ursula. Plus, destroying your child's property is technically mental abuse, and could have easily scarred Ariel for life. Viewers who wished Triton would stay as a polyp have a solid argument.
To say nothing of how he brushed off an innocent life nearly drowning to death as "one less human to worry about." Yeah, he definitely should have stayed as a polyp, remorse or not.
Red Oni,Blue Oni: Morgana is often seen as this, if we compare her with her elder sister Ursula. While Ursula is fat, has short hair, lives in a volcanic area, performs impressive magic tricks and plots very cleverly, Morgana is skinny, has long hair, lives inside an iceberg, turns out to be extremely goofy in casting magic spells (she didn't manage to turn back Undertow into its original big self after ''twelve years'' of attempts) and lacks the sister's self-control, gloating when she shouldn't. Even their deaths result completely opposite each other. Ursula melts in boiling purple goo after being impaled by Eric, whereas Morgana gets frozen alive by the Trident's beam.
Ron the Death Eater: Being on two opposing sides of an issue, both Ariel and King Triton have people who ignore all faults in one while demonizing the other.
Ariel also get some of this in regards to her parenting towards Melody in the sequel. Fans love to sham her by calling her a hypocrite because of how overprotective she was of Melody, ignoring the fact that Ariel did try to keep Melody from making the same mistakes she did. This is of course ignoring that Triton was being paranoid about humans in general when he tried to keep Ariel safe. Meanwhile Ariel was trying to protect Melody from a definite threat in Morgana.
Also bordering with a major case of It Runs in the Family and Adult Fear: Triton may have been paranoid, but his heart was in the right place, and he proved to love her daughter so much to sacrifice everything, including himself, to keep her safe and happy. Exactly what Ariel did: she just needed to be a mother herself to understand how hard is being a parent.
Seinfeld Is Unfunny: The movie seems a bit like a paint-by-numbers Disney flick these days. Literally everything about it was new and groundbreaking at the time. Merging a fairy tale with Broadway elements? This was the first film to really popularise that formula. So numerous animated films these days owe their existence to this one. Another element from this one, that its successor Beauty and the Beast missed: the musical elements were sort of justified in-universe: one of the main characters is a concert composer and Ariel's singing voice is a plot point. Ursula also delivers a very theatre-inspired monologue in her first scenes, something which the later Disney villains didn't do.
The scene of Ariel finishing her "I Want" Song reprise, which shows her singing on a boulder while a wave crashes behind her in the background, is almost always the one scene that you will see in Disney's advertising and commercial spots that mention this movie.
The underwater musical in "Under the Sea" may be another one.
There's a third one, the one in which Ariel rises from the ocean after being turned human by Ursula.
Squick: Ursula. All the time. Especially when talking to Ariel and performing a lot of giggling like a Burlesque entertainer.
Strawman Has a Point: Triton is the intolerant Jerkass telling Ariel how cruel and evil humans are, and Ariel's idealistic views all turn out to be right. But remember, humans catch and eat fish, which are 100% sentient in this mythos. Of course, humans don't realize that, and Triton destroying all of Ariel's stuff was a dick move. The Carnivore Confusion doesn't help matters much - in real life, fish eat other fish all the time!
Superlative Dubbing: Ariel's stunning Norwegian voice done by Sissel Kyrkjebø gained a lot of attention, to the point she went on to voice Ariel in the Danish and Swedish dubs as well. To further exemplify the beauty of Sissel's voice, she's also the echo-ey, sad voice you hear in the background on the Titanic soundtrack.
Pay close attention to Louis the chef's ditty "Le Poisson", which has the same melody as "Be Our Guest".
They Wasted a Perfectly Good Character: The Evil Manta. He was at first set up as the main villain of the animated series instead of Ursula, since the series takes place before the movie, and it would make a lot less sense for Ariel to make that deal with Ursula if she had already faced and fought against her before their first meeting in the movie. Only, after a while, Ursula did appear in the series, after which Manta only appeared in one more episode. Plus the possibility of him being the villain of the sequel instead of "Ursula's crazy sister".
Though not for lack of trying, Ursula was never quite as menacing in the show as she was in the movie. The only time she was about to cross the Moral Event Horizon was when she tried to kill the harmless "bad-luck creature" from the episode Against the tide.
In the series, so did the Evil Manta.
What Measure Is a Non-Badass?: People love to throw up the "Ariel is a stupid bitch and a bad rolemodel for little girls who THROWS HER LIFE AWAY FOR A GUY" pseudo-reason, without bothering to dwell into her reasons and psyche (she already wanted to see the human world, Eric was mostly the push she needed to take the decision to go there, etc). Apparently a woman isn't allowed to fall in romantic love ever, specially if it's a teenage girl with next-to-none real life experience!
King Triton in Ariel's Beginning. The guy lost his wife Athena in a pirate attack, and many years later he still can't listen to music without being reminded of that tragic happening. Through the whole movie he looks so sad and depressed of what he had lost, and his strained relationship with Ariel ain't helping him.
It gets worse: by the first movie, his relationship with Ariel is so damaged that she prefers trying her luck with Ursula than trusting him again, he's visibly distraught and blaming himself for her escape and, when finally after years of bickering manages to patch his relationship with his daughter, he's grimly reminded that Ariel forgave him at her own marriage. When he realizes that he's going to miss her, he also realizes that now Ariel has her own family to care for, and he can never, ever get back the time they spent bickering. And then, in the second movie, we find out that he didn't even get to be a grandfather for his (possibly) first granddaughter.
Ariel herself too. She's really good at looking like a kicked puppy.
Melody in the sequel after being humiliated at her birthday party.