Donatello and April make a bizarre discovery while investigating a scientist's disappearance.
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!!This episode provides examples of:
* BitchInSheepsClothing: Dr. Falco. He’s portrayed as a benevolent scientist, but in reality, ''he’s'' the one that mutated Rockwell.
* CentipedesDilemma: Mikey has this problem when he starts thinking about how to fight without thinking. Falco knocks him out without problem.
* ChainedByFashion: The mutant monkey has shackles on his arms, legs and neck.
* CombatClairvoyance: The mutant monkey, as well as Dr. Falco.
* ComicallyMissingThePoint:
** April in her conversation with Splinter, with a side of InnocentlyInsensitive.
** Earlier, Falco reveals he used Rockwell as a Guinea Pig. [[LiteralMinded Mikey]] states he turned him into a monkey instead.
* CrazyPrepared: Donnie's chart about how to hang with April.
* DiegeticSoundtrackUsage: When Donnie unveils the T-Phone, it's accompanied by the theme tune performed in the form of a ringtone.
* DontThinkFeel: The Aesop of the episode boils down to this. Splinter tells Donnie that he needs to learn how to "fight without thinking".
* TheEmpath: The mutant monkey. Also, April and [[KungFuClairvoyance Splinter]].
* EmpathicEnvironment: A rainy thunderstorm breaks out when Falco is revealed to be evil. As soon as the Turtles defeat him, all signs of a storm are gone.
* {{Expy}}: Dr. Falco is one of Herbert West from the ''Film/ReAnimator'' films, right down to having the [[Creator/JeffreyCombs same actor]].
* FreudianSlip: When Splinter is using Mikey as a demonstration of "fighting without thinking", he says "Mikey" even though he usually never calls the turtles by their shortened names.
* ImplausibleBoardingSkills: Mikey combines this with RoofHopping.
* InkSuitActor: While Falco is a parody of [[Film/ReAnimator Herbert West]], he also strikingly resembles his actor Creator/JeffreyCombs in the 80s.
* KickTheDog: After gaining psychic powers and defeating all four of the turtles with little effort, Dr. Falco rubs salt in Donnie's wound with this comment:
--> '''Dr. Falco''': By the way, do you ''really'' think you have a chance with April?
* LapPillow: April lets Donnie rest his head on her lap after he gets beaten up.
* MadScientist: Falco. Basically a TV-Y7 version of [[Film/ReAnimator Herbert West.]]
* ManiacMonkeys: Even after the Turtles learn he's not just a mindless monster, he's still quite dangerous when angered.
* {{Metamorphosis}}: Dr. Rockwell, from human to mutant monkey.
* MidSeasonTwist: April begins her training with Splinter and the Turtles acquire and actually manage to keep a live canister of Ooze.
* RedEyesTakeWarning: Falco's eyes become bloodshot after he injects himself with the psychic neuro-chemical.
* ReplacementGoldfish: Played pretty straight when Splinter asks April to train as a ninja because of her gift of empathy. Especially notable because afterwards it's obvious he's thinking of his lost daughter, Miwa.
* TheReveal: See WhamLine.
* ShesNotMyGirlfriend: Donnie says this again, only this time it was Raph who did the teasing.
* SinisterSilhouettes: The scene where Falco extracts the psychic neuro-chemical from Monkey Rockwell's brain.
* TheSpeechless: The monkey is the only mutant in the show at the time who can't talk. This’ll change in Season 3.
* StalkerWithACrush: Donnie makes a flow chart with every conceivable excuse or reason to hang out with April for any possibility. ''Every'' possibility.
* StealthInsult: When Splinter explains how to fight without thinking to Donnie, he uses Mikey as his example.
-->'''Splinter''': You see? Mikey does not think.
-->'''Mikey''': Thank you.
* TailSlap: After Splinter demonstrates Mikey's ability to dodge his attacks without thinking, he compliments him. Then he gets Mikey at the last second by tripping him with his tail.
* WasOnceAMan: Dr. Rockwell
* WhamLine: "I think this IS Dr. Rockwell."
** Later, "...then what broke out of the cage?"
* WhatTheHellHero: April isn't pleased to overhear the turtles laughing at Donnie when he's in pain
-->'''April''': Are you laughing at him because he's hurt?!
* WouldNotHitAGirl: Played with. The monkey beats the tar out of Donnie and starts to go after April. He gets as far as grabbing her and roaring in her face, but backs off after she talks to him. It's later revealed that the monkey was reading their emotions, so he was hostile when Donnie was hostile and calm when April was calm. Her gender had nothing to do with it.