Krang has created an age-reversing serum, which has the capability to de-age a living being into a helpless baby. He sends Kroolik with Shredder to infect the Turtles, but he managed to successfully revert only Michelangelo and Leonardo into little tots. Now Raphael and Donatello must find a way to revert them back to the normal state while dealing with the rambunctious kids, all the while dealing with Shredder and Kroolik.
In one of the most bizarre animation errors in the series up to this point, there is a moment near the beginning of the episode when Capt. Krulik introduces Grillox and the creature fires a finger beam at the Technodrome's entrance with Krang standing next to it. At the exact moment the laser hits, Krang starts to move out of the way and the shot changes to an image of the inside of the Technodrome, complete with a spot of damage as if the laser hit there, and Krang is zapped out of the shot in the same instant. The next shot has him standing right next to Shredder and Krulik as if he were calmly there the whole time.
In the scene where Krang explains what the serum does, Shredder's movements and facial expressions suggest he's laughing, but there is no sound to prove so.
When the turtles are leaving the restaurant, Raphael is seen holding little Michelangelo while Donatello is holding little Leo. But in the scene where they go through the door, Raph is holding little Leo while Donnie is holding little Mikey.
Raphael is only seen holding one pizza just before he and Donatello entered the Channel 6 studio before switching back to holding two as they enter it.
Bebop and Rocksteady are not seen or mentioned in this episode.
When Michelangelo and Leonardo are playing with April's computer, for a split second after the computer breaks, Leonardo replaces Michelangelo on the chair.
When Leonardo and Michelangelo revert to their teenage-selves and start fighting their enemies, they automatically pull out their weapons, but they didn't have them earlier when they were turtle tots, so where did they come from?
April's fanny pack flashes back and forth from grey to white when she leads Leonardo and Michelangelo out the door.
When Leonardo and Michelangelo look at their pizzas, they're facing the wrong way, as the toppings are facing the camera.
There appear to be no mushrooms on the pizza Leonardo gets as we see only red dots on it which is probably pepperoni.
The pizza crusts change to white when Leonardo and Michelangelo say, "No way," to Raphael when he wants them to eat the pizza.
When Leonardo and Michelangelo are eating their pizzas, the toppings appear to change as they go from what can be assumed to be pepperoni to something that looks like onion slices.
Donatello appears to pour the antidote on only one of the pizzas.