On his Vero account, Zack Snyder commented on some visual symbolism that a fan caught in Batman v Superman: Dawn of Justice, claiming that it would foreshadow something in the unmade second Justice League film.
A fan posted a screenshot of Wonder Woman and Batman standing over Superman’s body in the remains of a wrecked building. “Never noticed before. 3 crosses,” he said, alluding to the shapes formed by various metal beams around them.
“That’s a reference to justice league 2,” Snyder wrote in response, and then, when someone called this a “huge bomb,” he added “#untilitwasnt.”
Snyder directed Batman v Superman: Dawn of Justice which, along with Man of Steel and Justice League, built the spine of the DC Extended Universe. Unfortunately, his deconstructive films proved divisive, leading to a series of attempted course-corrections for the franchise.
While Snyder still began production of Justice League, which was originally supposed to be a two-parter, but left halfway through, being replaced by Joss Whedon. The two directors’ styles clashed and the movie proved underwhelming overall; since then, Snyder has offered hints on what his original plans were.
It is unclear how exactly three random crosses could have foreshadowed plot points in a hypothetical Justice League Part 2, except perhaps as symbiolism—would three characters have wound up dead If so, would it have been Batman and Wonder Woman themselves? Whoever it was, would they have stayed dead? (The “Knightmare” foreshadowed resurrected, evil Superman as the film’s villain.)
More obvious is the Christian symbolism: Snyder doubled down on the “Superman as Jesus” motif that began with Superman: The Movie, and the religious figure, of course, was crucified along with two other people. Likewise, this film had the hero both celebrated as a savior and yet hated by the masses before laying down his life.