Science Marches On: Explaining the good deeds they perform, one of the daughters of the air says that, "We fly to warm countries, and cool the sultry air that destroys mankind with the pestilence. We carry the perfume of the flowers to spread health and restoration." In other words, the daughters of the air are following the miasma theory of disease, which was widely accepted when the story was written.
Acting for Two: The English dub has the same actress portray the Sea Witch and Jemmy the cat. This has often led to viewers believing the cat is the witch in disguise.
Real-Life Relative: Subverted in the English dub with siblings Kirsten and Thor Bishopric. Kirsten plays Marina, the titular mermaid, while her brother Thor plays Fritz the Dolphin.
Unfinished Episode: There were plans for comics to expand on Ariel's mother. It was scrapped for being too dark. The character was later expanded on in Ariel's Beginning, the third movie, but vastly different. In the comic, dubbed Portrait of Life, her name was Atlanta and she befriended a human named Duncan. She dies saving Duncan from an avalanche a villain made. In the prequel her name is Athena and she dies by being crushed by a pirate ship, saving her oldest daughter. Her demise triggers Triton's hatred and distrust toward humans.
What Could Have Been: A comic written by Peter David called Portrait of Life was planned but scrapped for being too dark. It was supposed to be a backstory into what happened to Ariel's mother. Queen Atlanta (who had brown hair) befriended a human artist named Duncan. She would often pose for his portraits. A rival artist named Kole attempts to kill Duncan by setting off an avalanche; however, Atlanta pushes him out of the way, only to be crushed herself. Triton goes into a rage at his wife's death, accidentally causes Kole to fall off the cliff, and attempts to kill Duncan. He is stopped when he hears the voice of Atlanta telling him to spare Duncan. The comic ends with Triton leaving with an unfinished portrait of Atlanta.
A revised version of the musical that was first played in the Netherlands cuts several songs:
"Human Stuff" is cut, except in some versions aimed at kids where "Positoovity" is cut instead.
Ursula's song "I Want To The Good Times Back" was replaced with "Daddy's Little Girl". The new song reveals that Ursula murdered her all siblings, except for Triton.
"The World Above (reprise)" is replaced with "If Only (Triton's Lament)" in order to make Triton more sympathetic.
Both "I Want The Good Times Back (reprise)" and "Sweet Child (reprise)" are replaced with "Daddy's Little Angel (reprise)".
Scuttle's verse in "Positoovity" is cut.
The villain songs "Wasting Away" and "All Good Things Must Come to an End", along with an alternate reprise of "Poor Unfortunate Souls" that would be sung when Ursula transformed into Vanessa, were dropped before the tryouts and could only be heard on a leaked demo tape.
"Where I Belong" and Ursula's reprise of "Her Voice" were cut after the Denver tryout, though the former was reincorporated into later versions of "Fathoms Below".
Development Hell: The play was only supposed to be temporarily finished on Broadway, however 10+ years later and there's still been no news of a revival.