Batman's tank seen at the end of Batman v Superman: Dawn of Justice.
The denouement of Zack Snyder's Justice League also sees Batman rounding up criminals in Gotham City while aboard his massive tank from The Dark Knight Returns. Given the influence of Frank Miller's graphic novel on the Batman embodied by Ben Affleck, the appearance of the tank is a fun Easter egg, but also one without a clear explanation for its origin within the film itself. However, the Snyder Cut offers reason to think that Batman might have built the tank from Kryptonian technology, and might have originally had a different purpose for it, as well.
Batman's Tank Has No Comparable Previous Vehicle In The DCEU
Throughout the time audiences have seen The Flash). Even as well-prepared as Batman is, his tank does not correlate to the kinds of vehicles he has made use of. The Flying Fox might be an arguable exception, but it is introduced as an experimental military aircraft that Bruce is having difficulty repairing. It is only through the deep technological connection held by Cyborg (Ray Fisher) that the Flying Fox is finally able to take off. That leaves the question of Batman's construction of a massive battle vehicle like the tank an unanswered one, but the Snyder Cut provides a major clue.
Following the Kryptonian invasion led by General Zod (Michael Shannon) in his closest ally Alfred Pennyworth (Jeremy Irons) have developed a similar interest in Kryptonian weaponry and technology as the U.S. government has. Among the upgrades Batman makes to his armor are his gauntlets capable of withstanding energy blasts, which come in handy against Steppenwolf's Parademon forces and Superman's heat vision during his amnesiac resurrection. Naturally, one would hardly expect Bruce and Alfred to stop there in adapting Kryptonian tech to battle both human and alien threats. With Batman always upgrading his crime-fighting arsenal, there could be a connection to the tank's appearance in Zack Snyder's Justice League.
Batman & Alfred's Experiments Might Have Created The Tank
A vehicle like Batman's tank more than gets the job done in rounding up criminals, but the sheer size and combat capability of it make the tank equipped for larger threats. Batman's and Alfred's experiments with salvaged Kryptonian tech could provide the answer to the tank's origin. With alien threats to Earth emerging, including the mercilessly powerful Steppenwolf (Ciarán Hinds) and his Apokoliptian overlord Darkseid (Ray Porter), Bruce and Alfred's intent all along might well have been in creating a vehicle capable of handling large-scale threats beyond the criminals of Gotham City. The tank could also tie into how Batman once viewed Superman.
The fact that Batman previously saw Superman as an extraterrestrial threat might have been what initially motivated him to build the tank. Though Batman regards Superman as a sworn ally by the time of Zack Snyder's Justice League, his and Alfred's experiments with Kryptonian weapons might have begun sooner than within the movie itself. Even as Alfred balked at Bruce's hostility to Superman, Batman was as determined to craft a counter to Kryptonian threats as Jesse Eisenberg's version of Lex Luthor was. While Bruce may have theoretically begun work on the tank as a battle vehicle against Superman, the discovery of the silver bullet of Kryptonite might have drawn his attention away from it. Batman's change in perception of Superman could then have led him to re-evaluate building a vehicle like the tank, Bruce still seeing it as a valuable asset but changing his mind on its purpose.
The Dark Knight Returns's influences on Ben Affleck's Caped Crusader present him as a uniquely experienced and weathered cinematic portrayal of Batman. The story of Affleck's Batman still came with modifications from his Frank Miller-inspirations, and that likely extends to the presence of Batman's tank at the end of Zack Snyder's Justice League. Bruce Wayne's skills at innovation are second to none, with Affleck's Batman being the smartest version of the character yet. With his intellect and plenty of remnants of Kryptonian weaponry and technology scattered throughout Metropolis, the Dark Knight might have used such scraps as the basis for his most fearsome battle vehicle.
