- Adorkable: Donnie and Mikey elicit this kind of reaction, because of playing the part of the Dork Knight very consistently.
- Anti-Climax Boss:
- Poison Ivy gets mutated into a monstrous venus flytrap creature... which is rooted to the ground, and whose limbs are too short to reach all the way across the room. Our heroes don't even bother to fight her, instead just sticking to the walls and walking by while she futilely snaps at them.
- Robin approaches Baxter Stockman and tells him to get ready to fight. Baxter instantly surrenders, prompting Robin to point out how disappointing this is.
- Complete Monster: Shredder and Ra's al Ghul are the leaders of the Foot Clan and League of Assassins, respectively, who struck a deal in the past. Shredder would help Ra's build a machine, capable of spreading dangerous mutagen across Gotham City, while Ra's in return would provide Shredder with the location of the Lazarus Pit, which would grant Shredder immortality. Shredder, invading various corporations and killing the staff who happened to be there and stealing technology, was able to nearly complete the machine, only failing to acquire the Cloud Seeder. Hearing about the failure, Ra's Al Ghul changed their plans and took Shredder with him to invade Arkham Asylum, killing all the guards there and freeing prisoners, but not before taking the formula for Joker Venom from The Joker and giving him mutagen, so that he could mutate the inmates to distract Batman and the Turtles. After Ra's hired The Penguin to steal the Cloud Seeder, he and Shredder take it away, killing all of Penguin's henchmen and threatening to kill him as well when he demanded a payment. Hoping to combine Joker Venom with mutagen and create a far more dangerous substance, that would not only painfully mutate people, but make them homicidal and extremely aggressive, Ra's and Shredder prepare to spread this to thousands of citizens of Gotham, to create chaos and destruction, before repeating this process around the world.
- Ensemble Dark Horse: Mr. Freeze is one of the most popular villains of both the movie and the comic for his Only Sane Man moment before being mutated and his sheer formidability as a polar bear mutant.
- Fridge Brilliance:
- Although Two-Face's mutation into a deformed cat appears unfeasible and unnecessarily horrific, it makes total sense when one realizes that cats in real life are extremely rarely born with two faces, a condition called diprosopus, with the afflicted cats referred to as Janus cats. This not only provides a plausible result of the mutagen, but also fits in perfectly with Two-Face's theme of duality.
- Some take issue that the Joker's mutation is a cobra snake, thinking that some other animal fits him better. This is because being a snake shows that he is deceitful while being a cobra specifically is because he likes poisoning people, be it with regular poison or the Joker Venom. When mutated, he can now do it with actual poison on top of words and actions.
- Of course the TMNT would barge in on Batman's business. Gotham is based off New York City, so they are actually fellow city folk!!
- Gotham isn't terribly far from New York either, as most Batman media places it on the coast of the New Jersey side of the Delaware Bay - generally a 2-3 hour commute by car. As a hot spot for crime of the street, organized, and super varieties, it isn't too far fetched for Shredder to look into resource acquisition when it's so closeby.
- Fridge Horror:
- The two universes be in the same setting rather than some alternate dimensional shenanigans raises quite a few implications...
- The mutated Mook who was a T Rex was cured by having Robin throw multiple syringes into his body though his mouth. So when his body shrunk upon being cured...
- Harsher in Hindsight: In this movie, Bane tries (and fails) to break Donatello's back thanks to his shell. In the IDW comics, Bebop and Rocksteady not only succeeded in breaking Donnie's shell (with a sledgehammer), but it almost killed him as a turtle's spine is fused with the shell itself. Bane's attempt can be an uncomfortable reminder of that.
- Hilarious in Hindsight: This is not the first time Batman faced the TMNT and mentioned Bane, Harley Quinn and also Shredder
- Like You Would Really Do It: The retromutagen is said to have a 40% chance of fatal side-effects. But as soon as we see Batman get turned into a mutant, we all know that chance might as well be 0.
- Memetic Mutation: From the comic, there's a particularily memetic panelBatman: This is where my parents died, Raphael.
- One-Scene Wonder: The Juggernaut elephant mutant and the T-Rex mutant barely have a minute of combined screen time in the climax, but they're nearly as memorable as the mutated Arkham Asylum prisoners.
- Popular with Furries: Some of the Mutated Arkham Inmates are rather well-liked by some furries, for being well... being mutated animals of course. Hyena Harley Quinn is especially popular.
- Shocking Moments:
- It's an adaptation of Batman/Teenage Mutant Ninja Turtles. Made in animated format. An official one at that, which was previously thought to be a pipe dream at best. Nickelodeon and Warner Bros. has probably thrown open the doors for a lot more.
- Troy Baker voices Batman and Joker in the same project, being the first voice actor to do so.
- Batman fights the Shredder one-on-one. And Shredder WINS. It's only because he was feeling "merciful" that he didn't just finish the Dark Knight then and there.note
- The post-credits scene. Shredder emerges from the ruins of ACE Chemicals, but somethings off about him. He suddenly starts to laugh... which then turns into a deranged cackle that sounds rather familiar. He then turns towards the camera... and gives us a Slasher Smile Nightmare Face that shows that he has been jokerized!
- Signature Scene: Batman vs. Shredder. That alone is worth the purchase of the movie.
- Special Effect Failure: At one point, Cobra Joker lowers himself down from a balcony. That would be fine, if his body was long enough to reach. But we see the end of his tail go down just as slowly, giving the impression that he's floating down against the laws of gravity.
- They Wasted a Perfectly Good Plot: Damian's family relationship with R'as al Ghul not being directly referenced is a source of disappointment for many fans.
- What Do You Mean, It's Not for Kids?: It's definitely surprising that Nickelodeon was involved with this movie given how surprisingly dark and brutal it can get, particularly with the mutations, some of the graphic imagery like Leo's Scarecrow induced hallucination of his brothers dying and becoming rotting corpses, and some of the blood and swearing. Notably, Shredder graphically buries a throwing star in the forehead of one of his own Foot ninjas (NOT a robot!), Ra's al Ghul beheads an Arkham guard, and Shredder punches his hand blades THROUGH a guy.
YMMV / Batman vs. The Teenage Mutant Ninja Turtles