Herman the Horrible along with recruits Groundchuck and Dirtbag destroy the power source to the force dome shield leaving the city vulnerable. The Turtleoids accuse the TMNT of sabotage and throw them in prison. Despite all this, Donatello still appreciates Shellri-La for being a turtle planet, whereas Michelangelo says Shellri-La has none of the things that the Turtles appreciate on Earth, such as rock & roll, video games or pizza, and Raphael chimes in that the Turtleoids have proven themselves just as biased towards the TMNT as have humans back on Earth. Leonardo protests that they must escape and confront the two-headed monster Herman the Horrible, which all agree on that. Kerma helps the TMNT escape by giving them standard Turtleoid attire. As Donatello dons a Turtleoid robe he remarks at the irony; he could understand sneaking around disguised on Earth; a human planet, but here they were on a planet of turtles and they must once again sneak around disguised!
The turtles decide to end Herman the Horrible's reign of terror once and for all. After Leonardo discovers Herman is no more than a machine, Donatello blasts him with a Pulverizer Ray and Herman the Horrible is soon revealed to be no more than two corrupt Turtleoid leaders who are sick of just using gold for energy and want real gold things. They attempted to overthrow Shellri-La's government. After capturing Shredder's mutants as well the turtle teens decide to return home, but are at least thanked by Kerma for saving Shellri-La and says he may return to see them one day. Meanwhile Shredder's newly created Chrome Dome leads an army of Foot Soldiers to build a smaller version of the Technodrome named the Mini Technodrome. Once the turtles have returned they destroy both the new Technodrome and Chrome Dome. Raphael is sorry Donatello had to leave Shellri-La, but Don remarks he is glad to be back on Earth, for Shellri-La had no video games, and worst of all, no pizza!
- Leonardo (Cam Clarke)
- Donatello (Barry Gordon)
- Michelangelo (Townsend Coleman)
- Raphael (Rob Paulsen)
- Splinter (Peter Renaday)
- April O'Neil (Renae Jacobs)
- Shredder (James Avery)
- Krang (Pat Fraley)
- Rocksteady (Cam Clarke)
- Bebop (Barry Gordon)
- Groundchuck (Bob Ridgley)
- Dirtbag (Pat Fraley)
- Bork (Townsend Coleman)
- Dwork (Rob Paulsen)
- Chrome Dome (Peter Renaday)
- Kerma (Jan Rabson)
- Herman the Horrible (Pat Fraley and Bob Ridgley)
- TV Announcer (Townsend Coleman)
- Shell-Ri-La High Councillor (unseen) (Cam Clarke)
- Shell Ri-La City
- Shell-Ri-La City Hall
- Shell-Ri-La Jail
- Median Park
- Herman the Horrible's Lair
- Turtle Lair
Home media releases
- Teenage Mutant Ninja Turtles: Planet of the Turtleoids
- Teenage Mutant Ninja Turtles Season 10 (Bonus feature)
- Teenage Mutant Ninja Turtles: The Complete Classic Series Collection
- Teenage Mutant Ninja Turtles: Cowabunga Classics
- Groundchuck's right gauntlet flashes from red and back to green when Michelangelo hog-ties him with his grappling hook.
- The dark markings on Michaelangelo's shell are oversized after Kerma opens the hole in the force-dome.
- The blades on Raphael's sais are missing when Kerma hands Leonardo the force-dome door opening device.
- Shortly after Herman the Horrible finally enters Shell-Ri-La, Donatello can be see with Leonardo's colours.
- When the Turtles and April gather for Kerma's journey home, Donatello is seen with an intact bo-staff on his belt after his broke while fighting Chrome Dome, but is seen with the broken pieces on his belt back in the lair afterward.
- Groundchuck's metal face mask is coloured red after he and Dirtbag destroy the force-dome generator.
- Groundchuck: Hog-tied by a dang blasted turtle. How humiliating!
- Leonardo: Who'd've imagined it, The four of us in jail!
- Michelangelo: Yeah, it's a travesty of the entire system of criminal juris prudence!...Whatever that means!
- Donatello: Actually, I kinda like it!
- Raphael: Are you out of your shell Donatello?!
- Donatello: Oh, I'm just happy to be here, in a world of turtles, for turtles, and by turtles!
- Raphael: Have you noticed that the natives have not exactly been friendly?
- Donatello: Well, with time they'll get to understand us, and with time...I could learn to live here!
- Michelangelo: Dude, get a grip on your brain-pan, Think of all the things you'd be giving up. No pizza, no TV, no video games!
- Donatello: (scoffing) Oh, yeah. Also no hiding in sewers, no sneaking round in stupid disguises!
- Leonardo: Fellas, there's no time to argue about this. We've got to escape before that Herman the Horrible returns!
- Shredder: This is your wake-up call, Miss O'Neil. Don't you wish to see the finished construction? (showing April the Mini Technodrome) Behold! The Technodrome, Mark II!
- April: You built a mini Technodrome overnight?!
- Shredder: (cut to shot of Chrome Dome exiting the vehicle) It's amazing what you can accomplish when you have motivated workers. (He and Chrome Dome enter the vehicle) Farewell, Miss O'Neil! It's been nice knowing you!
- April: (watching helplessly) Why do I suddenly feel like a sitting duck?