The source of the mysterious crystals found in the lair appears to be an ancient subterranean city. This site is also the location where Donatello and the Turtles' monster allies disappear. The city is inhabited by the sole survivor of an ancient race; although he claims wanting to return the creatures to their original form, his true intentions remain unknown.
First Appearance of The Mysterious Entity/The Sole Survivor/The High Mage.
This episode provides examples of:
- Alas, Poor Villain: The Sole Survivor. The Turtles can't help but feel a bit sorry for him. He was just trying to repopulate his city so he wouldn't be alone, but went too far. Turns out he was not entirely honest.
- All Up to You: In the climax, Leo, Raph, and Don are trapped by the Entity's amulet's power. Mike is left all alone to fight him.
- Bittersweet Ending: The humans can't stray too far from the city without mutating, but at least they can find a way to permanently reverse their transformations.
- Casual Danger Dialogue: In the climax, Leo, Don and Raph are all trapped by the entity and Mike is left all alone to fight him off. They briefly have a conversation during this situation.Mike: (Looks over at his trapped brothers) You guys are a lot of help.
Don: Just get his amulet, Mikey, that's how he's controlling everything.
(The Entity starts attacking him with spears)
Mike: Before or after he bludgeons me with those things?
Leo: Preferably before. - Convection, Schmonvection: The turtles land on the shore of lava and suffer no ill effects from the heat. Justified while they were in the transport pod over it, though as the pod would likely be insulated against the heat.
- Dwindling Party: A non-lethal version, and an obvious shout-out to the common monster movie trope. The turtles and the friendly monsters (and the unfriendly) all slowly disappear, one by one, until only Michelangelo is left. He reunites with them all, though.
- Get A Hold Of Yourself Man: When Quarry starts panicking, Mike smacks him across his face.
- Hoist by His Own Petard: In the final fight between the Turtles and the Entity, Mike uses the Entity's own crystal bola against him and has him trapped in his own People Jars.Leo: Thanks Mikey, you really stepped up.
- Let's Get Dangerous!: Mikey after spending the previous two episodes being extremely afraid of the situation they are in, here, after all his brothers along with Quarry, Stonebiter and Razorfist get captured, he remembers the tower from his dream from the previous night and decides to go to it. There, he finds Quarry and the others and attacks the Entity and has to be stopped by Leo. Later, When his brothers are all trapped, Mike is left alone to fight off the Entity and he defeats him using his own weapon.
- Magitek: The Entity uses glowing bolos that can teleport anyone to the city, such as the ones he used to capture Donatello in the previous episode.
- Naked on Revival: Quarry as a human again. Much to the Turtles' surprise.
- Samus Is a Girl: Quarry.
- Subverted Suspicion Aesop: Mike doesn't trust the Entity, while his brothers do. Not only does the Entity want to keep the Turtles with him against their wishes, it is revealed that he was lying about his noble intentions.
- Well-Intentioned Extremist: The Sole-Survivor aka the Entity. He wants to help the mutant people return to their human forms, but only so they'll stay in the underground city and repopulate it. Though, he later admits that he was not entirely honest.
- What Happened to the Mouse?:
- Quarry mentions in the previous episode that other underground dwellers had been taken by the mysterious figure who turned out to be The Sole Survivor but after all of the captives are released the only monsters shown are the seven abducted over the course of the last two episodes, long after the time period Quarry described, and no other Underground Dwellers appear in the follow-up episode "Return to The Underground" after being temporarily re-mutated either.
- On a minor note, Donatello's bag that he carries with him was teleported along with him after the Entity captured him in the previous episode. But when Don shows up again, his bag is missing without any explanation. It is possible that the Entity destroyed the bag.
