This episode provides examples of
- Broken Aesop: The whole message of this episode is that nuclear power plants are bad. Because the plant was leaking toxic waste, the Turtles destroyed it to save the merpeople's eggs. In reality, destroying the plant (with an explosion no less) will probably make things far much worse, as it will scatter the toxic waste everywhere. The real kicker is that the plant was already in the process of being dismantled and the eggs could have been easily moved elsewhere.
- Burial at Sea: For the Merwoman after her death.
- Call Back: The merwoman gives April a vision of the history of her people, showing the revolution of Y'lyntis by the slaves. The Turtles first learnt about this in Season 3 "The Entity Below"
- Fish People: the merpeople
- In-Name-Only: A common complaint about this episode is that it changes a number of elements of the story it's based on (#28 of the first volume). TMNT Entity's review elaborates on this in the last few paragraphs.
- Last of His Kind: In the telepathic vision the merwoman showed to April, The merwoman claimed they was the last remaining people left.
- Non-Mammal Mammaries: the merwoman has breasts, despite the fact that her people lays eggs. Possibly justified in that the merpeople were originally mutated from humans, so they retain certain human features (such as being bipedal and having fingers etc)
- Preemptive Apology: Don does this to an employee at the nuclear plantDonatello: We don't have time for this! Please accept my apology.Worker: For what?Donatello: For this. (hits the worker with his bo.)
- The Smurfette Principle: the merwoman is the only female out of the five remaining merpeople