Much has already been said about Gossip Girl's 100th episode Monday night.

Heck, we're starting to wonder what hasn't been said about the milestone.

It’s Blair’s wedding! Georgina’s back! Love triangles/squares galore! So many Upper East Side events are just waiting to come to a head, for better or worse. But as we learned yesterday, one big twist remains a big mystery.

That bombshell, apparently comes at the very end.

“You have to see [the last few minutes] to believe them. I really think they will take people’s breath away,” EP Joshua Safran says. “Someone asked on Twitter, ‘Will we smile or cry at the end of the episode?’"

"And I said, ‘It will be more like a gasp.’”

Executive Producer Stephanie Savage, who we can only hope played a major role in crafting the upcoming installment, explains that the final moment was something that “had to happen” in the 100th episode.

“That’s one of the fun things about having a mature show in Season Five, you feel like you can really have some fun. In the first couple of seasons, you feel like you have to keep certain things very guarded and protected because the hope is that you’ll have to make them last a long time,” she says.

Safran adds: “What we can say is why we made that decision will become clear with future episodes because, obviously, you will learn more about why that has happened, how that has happened. You see, it was such an easy decision ... It wasn’t something we belabored over or had long discussions about. It really wasn’t.”

“Obviously [the end] changes things. And what happens in the episode for Blair, Dan, Chuck, and Serena will become a whole new world for them. Obviously, we pushed the 100th episode as a special episode."

"A huge wedding, a royal wedding - it's a big episode. But it’s also the 13th episode of the season. So, the season arc does continue. The 100th is a turning point, connected to everything happening before.”

What do you think goes down at the end of the wedding-themed extravaganza to come? What could shock us at this point? Sound off on where you see the show heading - Monday and beyond - in the comments!

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.