WARNING: The following contains major spoilers for Batman vs. Teenage Mutant Ninja Turtles.
As with any adaptation of a comic book, whether it be live-action, a cartoon or an animated movie, it's never exactly the same as the source material. With the Batman vs. Teenage Mutant Ninja crossover finally being made into an animated film, we get a chance to see just how loyal DC Entertainment and Nickelodeon were with the lore, as it involves two unique parties who can easily go bonkers on comic book pages.
But, as expected, the movie makes quite a few alterations. So, with that in mind, let's take a look at the biggest changes made as Shredder comes to Gotham along with the "heroes in a half shell."
IT'S ALL ONE UNIVERSE
In the first volume of the comic from James Tynion IV, Freddie Williams II, Jeremy Colwell and Tom Napolitano, the Turtles and Shredder were sent to Gotham thanks to Krang's interdimensional weapon, as the alien wanted to consolidate power for himself in their universe.
Here, it's all one universe, and the Turtles simply make the trek from New York to the Dark Knight's home, tailing Shredder. In the comic, Shredder allied with Ra's al Ghul to spread Joker Venom as a last resort after he didn't have a way back home. In the film, Shredder is aligned with the Demon's Head right from the very start, looking to disperse poisonous clouds across the world.
THE ROSTER CHANGES
In the comics, Casey Jones and April O'Neil play crucial roles as they hop dimensions trying to bring the Turtles home. Not to mention, Master Splinter was marooned with his "sons" as well in Gotham, fighting alongside the Bat-family and even helping to train Batman in a sparring session he'd lose to Leonardo.
The movie doesn't have any of these supporting players for the Turtles, but it does add Barbara Gordon, Batgirl, to Bruce's team. She also works at Wayne Enterprises, helping him decipher the truth about the Turtles and why Shredder's going after cloud seeders. Damian's also prominent from the start of this movie, whereas the comic had him coming in for the finale at Arkham Asylum. As for the villains, Baxter Stockman doesn't feature until the second volume of the comics, whereas in the movie, he's in his fly form from the start.
THE MUTAGEN ISSUE
Seeing as it was two separate universes in the books, the mutagen factor inside the Turtles' bloodstream was rendered inert, leaving them dying. Shredder found this out, destroying his teleporter so that the Turtles and Splinter could remain in Gotham and perish.
Here, as it's all in the same world. There's no issue with the mutagen and no death factor for the Turtles. This predicament saw them almost return home in the comics in order to survive, only to rally back and surprisingly join Batman in the finale. In the film, though, Batman chides them for their petulance, but they eventually make amends, attacking Arkham as a united front, having never entertained the thought of leaving Bruce's side.
THE MAN BAT DRAMA
The six-issue miniseries used Arkham as the climactic backdrop where Joker, mutated into a giant cobra, and Mr. Freeze, turned into a giant polar bear, were among the inmates fighting off the Bat-Turtle alliance. However, here, no heroes were mutated thanks to the upgraded Joker Venom and ooze Shredder and Ra's stole from Casey.
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The film drastically changes this, however, as Bruce is injected and turned into a giant Man-Bat after Ra's and Shredder steal the ooze from New York. Batgirl uses this info to create an antidote, thankfully curing Bruce of his animalistic ways, all to add a bit more drama than the books.
THE EPIC VILLAINOUS BRAWLS
The comic never had Batman and Shredder going one-on-one at Wayne Industries in the beginning as "Shred-Head" smoke bombed himself away from the fight. The film, though, does give us this clash, with Shredder using a special martial arts punch to put Bruce down.
In the comic finale, Shredder's taken down by Splinter, but, as the movie ends, seeing as Shredder is way too much for the Bat, Bruce distracts Shredder so Raphael can punch his lights out in a coordinated effort. As for Ra's, the comics had the four Turtles sync up and smash their shells into him, squashing him unconscious. The movie flips the script, though, by having him battle Leo in a one-on-one sword fight, only for Leo to use a kick to the crotch to defeat Ra's. Lastly, Batman used an Intimidator suit in the comics. Not so in the movie.
THE ACE CHEMICALS FINALE
The comics ended with Shredder, Ra's and the inmates beaten at Arkham, with April teleporting in to take the Turtles and Splinter home, while Bruce carted Ra's off to jail. The Turtles departed with Shredder in hand, with Raph leaving his red mask behind to remind Bruce they're like family.
The movie does things differently because Arkham's a mere distraction, leaving Ra's and Shredder at Ace Chemicals loading up the seeders. This culminates in Shredder falling into a vat of chemicals in a massive action sequence, turning into the Shredder Who Laughs, a maniacal Joker-like Shredder in the post-credits. Unaware of what happened, the Turtles and Bat-family chill in the cave, eating pizza.
Batman vs. Teenage Mutant Ninja Turtles is now available on Digital HD and arrives on Blu-ray and 4K UHD June 4. The film is voiced by Troy Baker as Batman and the Joker, Darren Criss as Raphael, Kyle Mooney as Michelangelo, Baron Vaughn as Donatello, Eric Bauza as Leonardo and Rachel Bloom as Batgirl.