The Turtles are summoned to the universe of the 1980s TMNT cartoon, where they team up with the Turtles of that cartoon against their respective versions of Krang/Kraang.
- Actor Allusion: Yes, '87 Raph and '12 Don get into it over their voice... er, voices.
- Alternate Tooniverse: The 87-Dimension is portrayed as this. It's brighter than the 2012-Dimension, is two-dimensional and their alternate counterparts rely on cartoon hijinks to fight.
- Always Someone Better: A downplayed example, but the 1987 Leonardo is a much more confident leader than 2012 Leo is. This is most obvious when the eight turtles prepare to attack 1987 Krang, and the other turtles follow 1987 Leonardo's battle plan and pretty much ignore 2012 Leo's protests that 1987 Leo not give orders to his team.
- Birds of a Feather: Both 1987 Michelangelo and 2012 Mikey hit it off during their first meeting, rather than attack each other the way the other turtles do. They also clearly get along a lot easier than the others.
- The Bus Came Back:
- The modern Turtles get to see Splinter again during a brief return to Earth.
- Also, the very end of the episode has the 1987 Turtles confront the same Kraathatrogon from The Manhattan Project, except this time, it plays out a little more and sees Tiger Claw slice his way out of the monster and meet the 1987 Turtles, beginning his journey back to Shredder.
- Canon Discontinuity: The events of Turtles Forever are not acknowledged here. There are, however, some plot similarities, particularly an attempt to destroy the Mirage comics universe in order to destroy all the others. Although it could theoretically take place before Turtles Forever from the perspective of the 1987 Turtles. Denied
by Word of God. note - Canon Welding: 1987 Krang is related to The Kraang in the TMNT 2012 Series. Kraang Sub-Prime even calls him cousin and casually talks about how 1987 Krang was banished by The Kraang into The Dimension X reality of the original cartoon. In the original cartoon, Krang was revealed to have once been part of a giant humanoid Saurian species instead of a talking brain alien that we know him as.
- The Earth-Prime Theory: Like in Turtles Forever, there is an attempt to destroy the Mirage comics reality in order to destroy all the other realities.
- Evil Versus Oblivion: Kraang Sub-Prime is furious with 1987 Krang upon learning that he was trying to destroy entire dimensions instead of conquering them.
- Flash Back: When Leonardo talks to Master Splinter, he sees Shredder kill him. This causes him to almost confess to Master Splinter that he and his brothers are from the future, and that Earth was destroyed.
- Fun with Subtitles:
- When The Turtles go back to their lair, 2012 Series Raphael uses sign language to tell the 1987 Turtles stay put and be quiet.
Raphael (using sign language): "Will you fine gentlemen kindly wait here? And please remain silent, or I will strike you repeatedly in the face and bodily regions." - Intra-Franchise Crossover: This is the second time in the franchise in which its succeeding iterations are in a Crossover with its preceding counterparts.
- Leaning on the Fourth Wall: Thirteen minutes into the episode, the Donnies tell the other Turtles there are only nine minutes left before all the bombs are set to go off. This equals to twenty-two minutes total, which is the length of the total episode.
- Let's You and Him Fight: The 2012 and the 87 Turtles fight briefly when they meet although the 87 Turtles were specifically trying to get the 2012 Turtles' help, 2012 Raph immediately assumes the device 87 Donnie had was a weapon.
- Loophole Abuse: 1987 Krang uses Kraang Sub-Prime's desire to kill the Turtles as license to destroy the entire Multiverse. After his plans are revealed and Kraang Sub-Prime gets pissed off, he even says, "You told me you wanted the Turtles destroyed at any cost."
- Medium Blending: Scenes set in the 1987 cartoon's reality are depicted in 2D Flash animation meant to imitate the hand-drawn style of the original series, albeit rather unconvincingly. Scenes set in the 2012 cartoon's reality are depicted in the modern 3D CGI animation. We get to see both sets of Turtles translated into the other art style. The Mirage comics universe is depicted as still image comic book panels that move like a Motion Comic, though the other Turtles, in this case both of the Dons, are still rendered in their native art styles.
- Mood Whiplash: The Turtles, and Leonardo in particular, are briefly reunited with Splinter thanks to all the dimensional hopping around. Leonardo starts to have a sit-down with his father/mentor and struggles to find the words to explain their situation. Then there's a brief Imagine Spot of the Shredder killing Splinter, just as he did/will do. It deeply unsettles Leo, and more than one viewer as well.
- Mythology Gag: The first several times 1987 Leonardo fights, he draws his katanas menacingly and... kicks ineffectually. In fact, for most of the episode the 1987 Turtles refrain from using their weapons directly on their enemies, which modern Raphael calls them out on.
- The episode's title is similar to "Transdimensional TMNT", the title of a sourcebook for Teenage Mutant Ninja Turtles & Other Strangeness.
- The first time 1987 Leo yells 'Turtle Power', the screen splits into a four-way cut of the 1987 Turtles that perfectly mirrors their character select screen poses from the first arcade game.
- This happy exchange:
2012 Mikey: Kraang Sub-Prime!- In the middle of a fight, 1987 Raphael produces a pizza out of nowhere, cuts off a slice out of it with his sai, and throws the rest into the camera, straight out of the original opening credits. Cut to a Kraang covered in pizza.
2012 Raph: Where the heck did you get pizza?
80s Raph: Gimme a break. - Out of Focus: April and Casey's only screentime in this episode was during the intro... and they were asleep.
- Shout-Out: Kraang Sub-Prime kicks 1987 Krang into a dimensional portal in a manner similar to how King Leonidas kicks an arrogant Ambassador into a well in 300.
- Stating the Simple Solution: Raphael questions why they simply don't destroy the pieces of the Black Hole Generator they already have to prevent their use. Donatello retorts that the Triceratons could still reverse engineer the technology from only one piece and Fugitoid hints that his plan to destroy them is a one use thing so they need to have all three pieces destroyed at once.
- Stealth Prequel: For the 1987 Turtles, this actually takes place before the events of The Manhattan Project. The ending shows an extended version of the scene at the end of that episode. Oddly, the lines already recorded for that episode are redubbed by the actors rather than them just recording additions to them.
- Stupid Evil: Kraang Sub-Prime gave Krang leeway to "wipe out the Turtles at any cost." Krang's answer to this means enacting a Class X-4 destruction of the 1987, 2012 and Prime Dimensions, something that is antithetical to the Kraang's plans of conquering these dimensions after literal thousands of years of planning.Kraang Sub-Prime: This is why I banished you to the Two-Dimensional Earth in the first place. Because you're an idiot! A moron! A dingleberry! So you know what? I'm kicking you back!
- Take That!: When they first arrive in the '87 Turtles' reality, Mikey is initially terrified that they might be in Pittsburgh.
- Villain Team-Up: The 1987 Krang is working with Kraang Sub-Prime.
- The Voiceless: The Prime Turtles from the Mirage Comics universe are completely silent during their appearance. It adds to the sense of menace they give off.
- Whole-Plot Reference:
- Pretty much Turtles Forever condensed into a 20-minute episode instead of a 90-minute movie, and having the 2012 Turtles take the place of the '03 Turtles. Some of the interactions like Modern Raph making fun of the belt buckles, or the two Mikes getting along are the same, as well as the Prime Turtles being the most aggressive and their universe being the lynchpin that holds it all together. This makes it odd that the '87 Turtles don't comment at all on going through this before, unless from their perspective this episode happened first. But then that opens up plot holes for why they don't comment on going through it before in Turtles Forever. See Canon Discontinuity above.
- According to the show runners, the 80s Turtles who appear in this crossover are alternate universe counterparts to the ones who met the '03 Turtles. Which make sense, as this bunch appear to be far more...competent (except fighting that is).
