The Triceraton Empire arrives, bent on the planet's destruction. As the Earth faces its Armageddon, the Hamato Clan and their allies are forced into an unthinkable alliance, while a new player emerges from the shadows.
- Actor Allusion: David Tennant is once again in a spaceship that visited the earth, rescuing people from doom. But this time, he is a robot, instead of just being involved with them.
- Actually Pretty Funny: A Triceraton can't stop himself from chuckling when he sees Zeck/Bebop dancing to distract him.
- Adaptational Heroism: Agent Bishop was a major antagonist in his original series, and here he is the heroic leader of the Utroms.
- Admiring the Abomination: Casey's reaction to the Technodrome.Casey: That is so awesome... and terrifying!
- Alien Invasion: To follow on the previous season finales, this finale features the Triceratons as the invaders. Though they are out to destroy the Earth as opposed to conquering or terraforming it.
- Anyone Can Die: Every single cast member who isn't one of the four Turtles, Casey, April, a supernatural being like the Dream Beavers, Professor Honeycutt, or a Triceraton is killed in the destruction of Earth.
- Badass Crew: The Foot is able to hold their own against the Triceratons, especially when the rest of the Hamato Clan joins in.
- The Bad Guy Wins: The Triceratons succeed in destroying the Earth.
- Shredder finally kills Splinter, though it comes at the cost of his own life as well. Not that he cares.
- Bait-and-Switch: When it's first mentioned, the psionic extractor is built up as a torture device used on only hardened war criminals. The idea that it will be used on Mikey seems like a dark turn, as though he's in for a scarring and traumatic experience. ...only for quite the opposite to happen, much to the Triceratons' bafflement. what was supposed to be dark and gritty quickly turns amusing. Not only does Mikey enjoy it immensely, but they only manage to extract information about pizza.
- Big "NO!": The Turtles' reaction to Shredder impaling Splinter through the back.
- Bloodless Carnage: After running his blade through Splinter, there is a lot of blade visible on the other side. Nevertheless, there's no blood to be seen either on Shredder's blade or on Splinter's body as he dies.
- The Bus Came Back:
- The Kraang return to New York en masse after having been ousted from the city back in Battle For New York - notably their leaders Kraang Prime and Kraang Sub-Prime (who's survived seemingly certain death again).
- Mondo Gecko and Muckman are called in to help fight off the Triceratons.
- Kirby puts in a brief appearance.
- Continuity Nod:
- The Technodrome hasn't been airborne in two years, since the first season finale (two years have also passed in real life since that episode).
- Shredder demands Karai's whereabouts from Splinter after her disappearance in "The Fourfold Trap".
- The Turtles meet Bishop in the meat shop they fought Tigerclaw in during "The Wrath of Tigerclaw" (which is openly acknowledged by Mikey).
- Once again, with their home destroyed (albeit on a planetary scale this time), the Turtles, April and Casey flee for parts unknown with Professor Honeycutt.
- Shredder's remarks that he cares nothing for the Earth or humanity in comparison to his grudge against Splinter finally come to pass.
- Chess Motifs: Bishop, unsurprisingly uses a white chess bishop as a calling card.
- Clean Cut: Bishop effortlessly slices a cow carcass into three pieces with a butcher knife.
- Curb-Stomp Battle: Even when the Turtles call in all their allies, it only takes a few minutes for the Triceratons to defeat them.
- Darker and Edgier: Compare this finale to the two previous finales where the Kraang attempt and succeed in conquering New York. This time, the entire planet is sucked into a black hole, with much of the supporting cast along with it.
- Darkest Hour: The Earth has been destroyed, and the only survivors are the Turtles, Casey, and April. You can't possibly get any bleaker than that.
- Death by Irony/Laser-Guided Karma: The Kraang sucked the Triceratons' planet into a black hole, the Triceratons return the favor.
- Diabolus ex Machina: Just as Splinter's about to shut down the black hole generator, Shredder skewers him.
- Disc-One Final Boss: The Kraang are set up as the season finale Big Bad again, but the Technodrome is promptly taken down by the Triceratons midway through the first part and they're not seen again.
- The Dreaded: The fact that Kraang Prime and Sub Prime are scared of the Triceratons really says something.
- Enemy Mine: Splinter barely persuades Shredder to ally with him for the sake of Karai's survival. Shredder turns on him the moment his back is turned.
- Even Evil Has Loved Ones: Shredder is convinced to join with Splinter to save Karai from being killed in the Triceraton invasion. However, Shredder kills Splinter before they can save the planet, proving once and for all that while Shredder may love his daughter somehow, it will always be less important than his desire for revenge on Splinter.
- Even Evil Has Standards:
- Mozar orders one of the Triceraton soldiers to use the Psionic Extractor on Mikey. The soldier quite hesitant to use it since the probe is meant for only the worst war criminals. Mikey ends up enjoying it tho.
- Tiger Claw is also appalled by Shredder (literally) stabbing Splinter in the back and dooming the entire planet.
- Evil vs. Evil: Kraang vs. the Triceratons, the Shredder vs. the Triceratons.
- Evil Versus Oblivion: While the Foot Clan are the Hamato Clan's mortal enemy, they recognize that if they don't help the Hamatos fight the Triceratons, all of them will be annihilated. Subverted with the Shredder, who pretends to go along with it to ensure Karai doesn't die along with it, only for him to put Personal Hate Before Common Goals and kill Splinter as he was about to shut down the Black-Hole Generator, leading to the destruction of the Earth.
- Godzilla Threshold: When the Kraang themselves are curb stomped by the Triceratons, Leo orders that everyone be summoned in to help fight the Triceratons.
- Splinter asks for an alliance with Shredder to save the planet.
- Humans Are the Real Monsters: Part of the reason the Triceratons are willing to destroy the Earth along with the Kraang. In a way, they're proven right when Shredder's treachery allows them their victory.
- Impaled with Extreme Prejudice: Splinter is wholly impaled from the back by Shredder.
- Last Episode, New Character: Both Agent Bishop and Professor Honeycutt.
- Make Way for the New Villains: The Triceratons establish themselves as the bigger threat when they destroy the Technodrome and kill Kraang Prime and Sub-Prime.
- Mood Whiplash: So, Splinter was murdered, every other character minus the Turtles, April, and Casey are dead, and the Earth was swallowed up by a black hole.,..then Fugitoid offers Mikey some hot cocoa. Casey's excitement at having adventures in space also counts as this since he just saw the whole planet sucked into a black hole, which would include his dad and sister.
- My Species Doth Protest Too Much: It is revealed that Bishop is a member of the Utrom (Kraang who defected from the Krang hivemind).
- Mythology Gag:
- In the 2003 series, the Triceraton invasion opened the third season. Here, it instead closes the season.
- Both Triceraton invasions involve a turtle getting kidnapped.
- The extractor used on Mikey is similar to the one used on Donnie in the 2003 show. Although Mikey had it easy.
- In the 2003 show, the Triceratons are searching for the Fugitoid/Professor Honeycutt. In this version, the professor saves the turtles, April, and Casey.
- The Utroms were a peaceful, benevolent race of aliens, and it was assumed that the Kraang being villains was a case of Adaptational Villainy regarding the species. Here, the Utroms indeed exist, albeit as a smaller offshoot of the Kraang.
- Bishop revealing himself to be an Utrom is reminiscent of Ch'Rell's outing in the previous series. Also, Dr. Jordan Perry was planned to be revealed as an Utrom in a similar fashion.
- Both Bishops made their debut during their respective Triceraton invasions.
- The previous incarnations of the Triceratons were also depicted as being at war with another hostile race of aliens, and were the dominant power in the war.
- Splinter being killed could be a reference to the Next Mutation's cancelled second season where the writers were planning to kill off Splinter.
- How Shredder is A-OK with dying as long as he knows Splinter perishes along with him heavily references Turtles Forever in that the Utrom Shredder doesn't care about the eradication of Turtle Prime entailing his death as well.
- No-Sell: The Mind Rape device fails to have an effect on the scatterbrained, pizza-obsessed Mikey.
- Pet the Dog: During their fight with the Triceratons, Tiger Claw saves April and Casey from being attacked.
- "Ray of Hope" Ending: Splinter's Enemy Mine with the Shredder backfires as the latter's Chronic Backstabbing Disorder flares up at the worst possible moment, allowing the Triceraton Empire to detonate their device that will suck Earth into a singularity. Before Earth is destroyed, the Turtles, April, and Casey are rescued by the Fugitoid, who claims they're about to embark on a wondrous adventure.
- Revenge Before Reason: Shredder is willing to let the entire Earth be destroyed with him on it just to kill Splinter.
- Season Finale: The third one.
- Security Cling: Despite the gravity of the situation, Bebop and Rocksteady holding each other as they die is still a pretty comedic example.
- Shout-Out:
- While being sucked up into the black hole, Leatherhead and Rockwell recreate Michelangelo Buonarroti's "The Creation of Adam".
- The shots of the Triceraton ship's lasers about to fire bring a certain alien invasion film to mind
- Donnie once again channels Scotty.
- A character played by David Tennant shows up in the midst of the end of the city to save a few specific survivors while highlighted by a white glow, (The Fires of Pompeii) and then outruns a blackhole in his ship. (The Satan Pit)
- Smurfette Principle: Of all the people who battle the Triceratons in Part 2, April is the only female one.
- Sudden Downer Ending: It looks like the combined might of the Hamato and Foot Clans might be able to destroy the black hole generator… then Shredder kills Splinter, dooming the Earth to annihilation.
- Too Kinky to Torture: Mozar has Mikey put into the Psionic Extractor, an information extracting device so horrible that they only reserve it for the most hardened and guilty of war criminals. Apparently it has never been used on turtles and/or mutants, as it gives Mikey a Mushroom Samba rush that leaves him begging to be put through more of it when they turn it off. They didn't even get any valuable information, the only thoughts Mikey ever has being about pizza.Michelangelo: Dude, why did you stop? That was better than, like, 100 million roller-coaster rides in outer space!
- Trash the Set: The entire Planet Earth is gone by the finale.
- Vomit Discretion Shot: Subverted. When Raph pukes in zero-g aboard the Kraang ship, there's a blink an you'll miss it glimpse of airborne vomit. Then Donnie activates the artificial gravity and gets a faceful of falling sick.
- Wham Episode: Shredder seemingly kills Splinter, the Triceratons successfully activate the black hole bomb, destroying Earth, and the Turtles, along with April and Casey, are rescued by Professor Honeycutt.
- The Worf Effect: The Kraang are very quickly taken down by the Triceratons.
- Ironically, the Triceratons' leader, Mozar, is voiced by Worf himself.
- Worth It: Shredder gives it straight that he doesn't care that he just doomed the entire planet including himself; he finally got to kill Splinter, and that's all that matters.Tiger Claw: Shredder... what have you done?!Shredder: Hamato Yoshi is finished. The Earth can be destroyed for all I care — I HAVE FINALLY WON!
