Donatello experiments with Mutagen in an attempt to find a cure for April's mutated father. But one of his experiments goes wrong and Timothy is accidentally unleashed in the city.
This episode provides examples of:
- A Day in the Limelight: April and Casey get a fair bit more of focus in this episode than the Turtles do, as most of the episode is spent with them fighting Mutagen Man.
- Continuity Nod: April is still mad at the turtles and is trying to avoid them at all costs.
- Crazy Jealous Guy: Donnie doesn't respond to April and Casey's "date" too well.
- Early-Bird Cameo: We get another appearance from Irma before her actual debut when April meets Casey. We only get a full view of her from the back and from the front, the only part of her face we see is her jaw.
- Establishing Character Moment: You'll get a rather good idea on what Casey is like when he says that he'd like to be either a professional hockey player or a Bounty Hunter.
- Fantastic Racism: Well, specism, but still. Donnie demanded to know if April "liked" Casey because he was human.
- Freeze-Frame Bonus: The copyright notice on the video tape.
- From Nobody to Nightmare/Took a Level in Badass: Pulverizer's awful combat skills have been replaced with super strength and acid hands. He can even use his stalks as rope.
- Hypocritical Humor: Leo immediately Lamp Shades how rich it is for him to call Super Robo Mecha Force Five Team Five awful when his brothers were always complaining about Space Heroes.
- It's All About Me: Again, in this episode, Donnie wants to cure Kirby so that April will like him. In addition to that, he gets jealous when he sees her with Casey in the park. Really, he should focus on the other people involved other than April.
- Male Gaze: When April is fighting Mutagen Man, it's obvious what Casey is staring at.
- Missed Her by That Much: Just after the Turtles split up to find April, we see her walking by the building they were just standing on.
- Mythology Gag: The speaker Donnie attaches to Mutagen Man's tank has the word "Laird" on it, a reference to Peter Laird, co-creator of the original TMNT comics.
- When Casey gets into a fight with Mutagen Man, one of the first things he does is yell "GOONGALA!", which is a catchphrase of his in the comics and 2003 show.
- Never My Fault: Mutagen Man blames the turtles for his mutation despite the fact it was his fault and the turtles had advised against it and tried to stop him numerous times.
- Nice Job Breaking It, Hero: Donnie ranting about his problems with April led Mutagen Man to try kidnapping her so he could have a friend.
- Poor Communication Kills: Mutagen Man tries to talk to April, but his speech limitations and the fact that he's a dangerous mutant get in the way.
- Revenge Myopia: Mutagen Man cites the fact that the turtles are attacking him as just another reason why they don't deserve April. Never mind that they were doing this to protect April from him...
- Stalker with a Crush: Donnie stalks April in the first third of the episode. He becomes infuriated that April was "seeing" a human boy.
- Take That!: Towards dubbed anime when one of the turtles complains the characters' dialogue don't match their lip movements.
- That Man Is Dead: During their final battle, Donnie laments that they need to keep Mutagen Man alive so that he can find a cure for the mutations, but Leo puts his foot down and tells him like it is with this exchange:Leo: Donnie, we have no choice! Whatever the Pulverizer— Timothy was, is gone now.
Donnie: But if we destroy him, I might never find a retro-mutagen! What about April's dad?
Raph: What about April? - Troll: Splinter's way of telling Donatello to stop trying to force his feelings on April? Allegedly train him to enjoy falling down!
- What Happened to the Mouse?: This marks the final appearance of Timothy, despite this being his only episode appearance as Mutagen Man. After being duped by the turtles into drinking a spiked canister of mutagen that freezes him completely, Mutagen Man is never seen nor mentioned again for the rest of the series, despite Donnie once again promising Timothy that he will cure him of his mutation. We can only assume that Timothy is still frozen in the turtles' lair to this day...
