The fifty-sixth episode of Adventures of Sonic the Hedgehog.
When an undersea world is threatened by Captain Memo and his octopus sub, Sonic spreads a rumor that Memo plans to attack Robotnik next. When Robotnik hears of it, he launches an attack on Memo with a Robotnik-shaped sub, but Sonic's plan backfires when Robotnik decides that he will team up with Memo to conquer the undersea world. With the help of a friendly school of porpoises, and the Mer-People of the undersea world, Sonic sends Robotnik and Memo floundering away.
This episode provides examples of:
- Alliterative Name: Merna the Merhog.
- Big Guy, Little Guy, Lieutenant Bananas and Captain Memo, respectively.
- Early-Installment Weirdness: Unlike his canon video game counterpart, Sonic is shown to swim very well in this episode.
- Eaten Alive: At the end of this episode, after Robotnik says, "I hate seafood and hedgehogs!", he is swallowed whole by a shark.
- Exit, Pursued by a Bear: After his sub is destroyed, Robotnik is chased away by a school of sharks.
- Giant Squid: One takes Captain Memo and Luitenant Bananas away after Tails and the Merhog Queen tie them up.
- It Came from the Fridge: Grounder at one point opens Robotnik's fridge and gets attacked by three-year-old lasagna that came to life.
- Meaningful Name: Throughout the episode, Captain Memo asks Lieutenant Bananas to take a memo.
- Office Golf: Robotnik plays a round and even provides his own commentary.Robotnik: If Dr. Robotnik can sink this final putt, he'll win the Mobius Tournament of Champions and the grand prize of the dictatorship of the universe.
- Our Mermaids Are Different: This episode features merhogs, who are part hedgehog and part mermaid.
- Screw This, I'm Outta Here: Near the end of this episode, when Captain Memo's sub sinks, Memo asks Lieutenant Bananas to take a Memo. Bananas tells him, "No, you take a memo! Abandon ship! Gorillas and children first!" and swims away.
- Shamu Fu: Robotnik hits Scratch with a fish when he and Grounder interrupt his battle against Captain Memo to tell him that Sonic tricked him into fighting him.
- Shoot the Television: At the end of this episode's first act, Robotnik hits a golf ball at his computer screen when he vows to destroy Captain Memo's octopus sub.
- Shout-Out:
- This episode's title is a reference to the Hans Christian Andersen fairy tale, The Little Mermaid, perhaps best known for its 1989 Disney film adaptation.
- When Sonic rides a killer whale, he says, "Hi-ho, Killer Whale, away!"
- Toilet Humor: Perhaps a literal example; Robotnik is in his sub's restroom when Scratch announces that he's spotted Captain Memo. A flush sound effect can be heard, and when Robotnik opens the door, a roll of toilet paper unrolls out it.
- Villain Team-Up: Once Scratch and Grounder tell Robotnik that Sonic tricked him into fighting Captain Memo, the two villains team up to destroy Mertopia.
- Water Is Womanly: Merhogs live underwater and are a female-only race.
- You Have Outlived Your Usefulness: After Scratch and Grounder get on Robotnik's bad side in his sub, he loads them into its torpedo tube and fires them at Captain Memo's sub.
