- Leonardo (Cam Clarke)
- Donatello (Barry Gordon)
- Michelangelo (Townsend Coleman)
- Raphael (Rob Paulsen)
- Splinter (Peter Renaday)
- April O'Neil (Renae Jacobs)
- Vernon Fenwick (Peter Renaday)
- Irma Langinstein (Jennifer Darling)
- Shredder (James Avery)
- Krang (Pat Fraley)
- Bebop (Barry Gordon)
- Rocksteady (Cam Clarke)
- Rat King (Townsend Coleman)
- First Explosive Thief (Rob Paulsen)
- Second Explosive Thief (Townsend Coleman)
- Gypsy Woman (Jennifer Darling)
- Cheese Shop Owner (Pat Fraley)
- Man in Street (James Avery)
- Turtles' Lair
- Rat King's Lair
- City Sewer System
- City Airport
- Cheese shop
- Pet shop
- Flaming Turkey restaurant
- Channel 6
- Turtle Blimp
Home media releases
- Teenage Mutant Ninja Turtles Season 4
- Teenage Mutant Ninja Turtles: The Complete Classic Series Collection
- Up until this point in the cartoon series, mutagen has always been depicted as a glowing pink in color. Starting with this episode, it is changed to green, as it is typically colored in the vast majority of Turtles media.
- First time Irma and Vernon are turned into mutants, the second being into insects in "Revenge of the Fly".
- Shredder spoke to Rocksteady and Bebop with his Com-Link instead of watching them on the portal's view screen.
- Final appearance of the Rat King's flute until he acquires another one in "Night of the Rogues".
- Donatello accompanied the other Turtles in pursuing Bebop and Rocksteady in the plane, but was later seen riding the Turtle Blimp after he, the other Turtles, Vernon and Irma had fallen off the plane! In fact it would have been more logical for him to leave the others to fight while he got the blimp from the lair.
- When Rocksteady spoke to Shredder on his comlink, he wasn't holding the comlink.
- Donatello's belt was colored purple after April asked the Turtles if they'd seen Vernon and Irma.
- When the Turtles leave the Rat King's lair, Leonardo has Raphael's colors
- The mail box outside Channel 6 that it seen when Rat King goes topside, is misspelled as "US Male".
If the Rat King really wanted to turn April into a rat, why didn't he just splash the mutagen on her instead of tying her up next to a device that would drip the mutagen onto her?