This article contains massive spoilers for the ending of "Batman v Superman: Dawn of Justice.

If you're one of the many, many people that saw "Batman v Superman: Dawn of Justice" over its opening weekend, then you know that the film ends with one major surprise that will surely have big ramifications for the DC movie-verse moving forward. Director Zack Snyder talked about the film's ending in a spoiler-filled interview with Buzzfeed, revealing how they kept the scenes in question under wraps.

In the film, Superman dies at the hands of Doomsday while delivering the killing blow to the Kryptonian monster. "I felt it was inevitable," said Snyder of Superman's death. "Even when we were working on 'Man of Steel,' I was like, 'Gosh, what are we going to do with this guy? He's a pretty tough cookie.'" Snyder spoke to the need for the growing franchise to have a reason to form the Justice League, and Superman's death would lead into that. "The catalyst, the need for the Justice League, has to rise from something," he said. "To me, [Superman's death] solved so many great problems."

Considering the title of the film and the inclusion of Doomsday, the villain that killed Superman in the massively popular "Death of Superman" comic story from almost 25 years ago, Snyder says he was "shocked that people did not immediately jump to the conclusion. I think they just felt like, 'That's impossible. They're not going to kill Superman.' I mean, a couple people did [figure it out], but then they were all yelled at. It was funny."

"BvS" then concludes with funeral scenes for both Clark Kent in Smallville and Superman in Metropolis. In order to keep these scenes secret, the crew had to be very careful. Clark Kent's funeral was referred to as a "harvest festival" during production and the scene with his open casket featured just the film's crew as extras. Superman's funeral was kept vague, with people assuming that the casket draped in an American flag belonged to the president.

"I would tell [the extras] that there was a huge tragedy, and Superman saved the day," said Snyder. "But there was a lot of emotion around what happened, and it's a sad day. Everyone worked it out in their own heads. There was one fireman who was really crying. I was like, 'Wow, that's great.'"

While he went back and forth on it, he did ultimately include a final split-second scene wherein the dirt on Superman's casket begins to levitate, thus implying that his death may not be final. When asked if fans should be worried that Superman's movie death is irreversible, he replied, "No, they probably don't have to be freaked out by that," Snyder said. He added, laughing, "But, we haven't filmed it yet, so..."

"Batman v Superman: Dawn of Justice" is in theaters now.