DC Fans Petition Warner Bros. to Release Zack Snyder Cut of 'Justice League' Zack Snyder had completed several months of work on Justice League when Joss Whedon came on board to write some additional scenes for the superhero ensemble. Unfortunately, Snyder had to step away from the film due to a family tragedy, leaving Whedon to oversee post-production. By Warner Bros.’ account, about a quarter of Justice League was reshot by Whedon, but it’s been heavily rumored that the Avengers director actually reshot something like 80 percent of the film.