Warning: The following contains SPOILERS for Batman: The Long Halloween, Part 2.

The animated film adaptation of Batman: The Long Halloween teases a follow-up film involving the Justice League. It has been theorized it could be setting up the upcoming Injustice movie, which is the only DC Comics animated film currently in the works at Warner Bros. Animation. However, the film also leaves the door wide open for adaptations of the prequels and sequel of the original Batman: The Long Halloween graphic novel.

Batman: The Long Halloween is one of the most influential Batman stories of all time. Originally published as a 13-issue follow-up to Batman: Year One, each chapter detailed one month in Gotham City and the killings perpetrated by a serial killer dubbed Holiday, due to their habit of shooting people to death on major holidays. This set the stage for an epic gang war between the organized crime families overseen by Carmine "The Roman" Falcone and the supervillains who were beginning to take control of the city in the shadow of Holiday's murders, which seemed to target the Falcone family and their associates.

Related: Batman: The Long Halloween Part 2 Ending Explained

Despite making a number of changes from the comics, a Batman: The Long Halloween follow-up film based on the original's direct sequel, Dark Victory, could be in the cards. However, there have been no formal announcements about this or any Justice League movie following after the lead established by the latest Batman movie. This has left fans wondering what to expect, while being certain to expect something.

Batman: The Long Halloween Part 2 Sets Up A Sequel

Batman The Long Halloween Part 2 Green Arrow and The Flash in Post Credits Scene

Batman: The Long Halloween, Part 2 contained a post-credits scene in which Alfred the Butler answered the doorbell at Wayne Manor, anticipating trick-or-treaters on Halloween Night. Instead of finding costumed children, however, he found The Flash and Green Arrow. Unruffled by the unusually dressed visitors, Alfred called out to his off-screen employer, saying "It's for you, sir." This appears to be setting up some kind of story involving the Justice League and some have speculated it may be setting up Injustice, which is the next DC Comics animated adaptation scheduled for release.

What Film Is The Long Halloween Setting Up?

Batman and Robin leap into action in Dark Victory.

While it is possible that Batman: The Long Halloween, Part 2 is setting up for the story Injustice, it seems unlikely, despite Green Arrow and The Flash playing major roles within that storyline in the comics and the video games that inspired them. Everything known about the Injustice animated movie suggests that it will be its own beast and not tied into a larger continuity, much like its source material. It seems more likely that there is another Justice League project in the works, which Warner Bros. Animation has not announced yet, that may build off of the foundation established by The Long Halloween and Superman: Man of Tomorrow. It is possible, however, that the studio could produce a direct sequel to Batman: The Long Halloween based on Dark Victory, the comic book sequel series which revamped the origin of the first Robin, Dick Grayson. WB could also adapt the Haunted Knight trilogy: a collection of one-shot comics produced by writer Jeph Loeb and artist Tim Sale that led to the creation of The Long Halloween.

Batman: The Long Halloween Part 3 Cast

Jensen Ackles in Supernatural and his version of Batman in The Long Halloween, Part One

No casting announcements have been made for a Batman: The Long Halloween sequel at this time, although the cast list for the Injustice animated movie has been announced and there is no overlap between them. Presumably, if Warner Bros. Animation does produce adaptations of the other Jeph Loeb and Tim Sale comics tying into The Long Halloween, the studio will want to retain as much of the original cast as possible, including Jensen Ackles as Batman. Unfortunately, it would need to recast the role of Catwoman, due to Naya Rivera's tragic drowning death in July 2020.

Batman: The Long Halloween Part 3 Release Date

Batman in Batman: The Long Halloween, Part One.

At this time, there is no official release date for a Batman: The Long Halloween follow-up film. The only upcoming DC Comics animated film confirmed in production at the time of Batman: The Long Halloween, Part 2's release was the adaptation of Injustice: Gods Among Us. That film is said to be planned for a Fall 2021 release.

More: DC's Injustice Animated Movie Cast Guide: Every Confirmed Character