We've known for a while now that Zack Snyder was responsible for Justice League's after-credits scene but it turns out the filmmaker didn't shoot all of it. Originally, Deathstroke was set to be the lead villain in Ben Affleck's The Batman and it's safe to assume this scene originally depicted Lex Luthor hiring him to go after the Dark Knight because the video below reveals a key change made by Joss Whedon.
As you can see by heading to the 2:38 mark in the video below (which was shared by a member of Justice League's camera and electrical department), it seems Whedon added the line, "To put it plainly, shouldn’t we have a league of our own?" That was obviously a way to tease the arrival of the Injustice League somewhere down the line while simultaneously removing any links to The Batman.
Seemingly in response to this footage surfacing, Zack Snyder has taken to Vero to share a very cool behind the scenes shot of Joe Manganiello suited up as Deathstroke. When a fan asked him about the change in dialogue, he responded: "What is this?" The filmmaker has previously said that he hasn't watched Justice League so chances are this change has come as something of a surprise to him.