Eric, after calling down the girls shows his rarely used talent at Deadpan Snarking.
Ariel: Just give us two minutes.
Eric: Right, two minutes... (mumbles to himself after closing the door) Now, where have I heard that line before?
Sebastian's reaction to Triton saying that he will watch over Melody.
"And these WHOPPERS popped out!"
The reprisal of the chase between Chef Louis and Sebastian when Louis instantly recognizes Sebastian and says, "YOU!"
And the conclusion:
"DEATH TO THE CRAB!"
In true Disney Villain tradition, Morgana gets some of the best lines in the film.
Morgana: (at the christening) Ursula would love to have come, but something came up. Now what was it? Oh yes! You all SHISH KABOBBED HER!
Tip and Dash's arguing over if Melody can stay with them or not. And Tip keeps using the same "You can't fly either!" excuse twice.
"Another plan, perfectly executed."
At the beginning where Scuttle is looking at the window; with preparations for Melody's 12th birthday party
Scuttle: Whoo-wee! This is gonna be some kinda shindig! Yes, sir a real swanky...soirée as they say! There's just one thing missin'...THE GUEST OF HONOR!
Sebastian tries to give Melody a lecture about swimming - but she interrupts him by reciting the exact lecture he was going to say, implying he's said it several times. She also does a near-perfect imitation of his voice. Sebastian deadpans "stop that."
When Melody meets the merboy, she's so tongue tied she can't say her name properly. So the boy introduces her to his friends as "Mel-Mel". And since he doesn't see her again until the end of the film, one wonders how long before she was able to correct him.
A hysterical Sebastian sobbing his eyes out on the hem of Ariel's dress and blowing his nose on it when he reports Melody ran away.
Sebastian: All right, Sebastian, you must remain calm. This is not your fault. All you have to do is go in there and calmly explain... that Melody has run away. No reason to lose your head. Whatever you do, you absitively positutely...must not panic. Ariel: Melody! Sebastian: AAAH!!! MELODY'S GONE! MELODY'S GONE! Ariel: Sebastian? What-what are you doing here? Sebastian: (sobbing hysterically) It's all my fault! I tried to stop her!! I DON'T DESERVE TO LIVE!!! (wails) Ariel: Gone? Gone where?! Sebastian: Out...out... to the sea. (blows his nose on Ariel's dress) Ariel: What do you mean? Where could she be going?
At the climax where Morgana is using the trident on everyone to bow down to her...well,...except Eric who's unconscious from Ariel saving him from drowning (again). Seeing Ariel being forced to bow with Eric laying unconscious right next to her makes the climax a bit of a Mood Whiplash. Now that is funny.
Melody jabbing Morgana's tentacle with the trident and Morgana holds her tentacle in pain.