Once Upon a Time's Rebecca Mader accidentally spoiled the series finale 

\'s Rebecca Mader accidentally spoiled the series finale

Rebecca Mader totally spoiled the series finale of

ahead of Friday’s emotional hour — completely and utterly by mistake.

During the series finale, Wish Rumple (Robert Carlyle) sought to separate all fairy tale characters for eternity but was thwarted by Rumple, who sacrificed his heart to save an ailing Hook (Colin O’Donoghue). To ensure that no one would ever be alone again, Regina (Lana Parrilla) casts a new Dark Curse, powered by love, that brings all the realms together in Storybrooke — she’s crowned the leader of this new combined realm as The Good Queen.

The problem? That’s exactly what Mader had hoped would happen in the series finale, which is why she had no problem telling fans that during a recent convention, totally unaware she was spilling the show’s final secret.

“Someone asked me at the convention, ‘If you could write the finale, what would it be?’ And I hadn’t read it yet, even though it was in my inbox. I’m like, ‘You know what I want? I want all the people from all the realms to come together, and all the old cast, and all the new cast, and we all just move to Storybrooke, and we all live happily ever after, and we all just get on.\'”

Mader said the crowd went wild because they loved the concept. Little did she know, the script that was sitting in her email inbox depicted that very ending. “Then I read the script, I’m like, ‘They’re going to think I knew this,\'” she says with a laugh, insisting it was an honest mistake. “That’s what I wanted. I wanted everybody from everywhere to come together, because we’ve been to so many worlds, and so many realms, I’ve been all over the bloody place. I just wanted to put everyone together, and I just really wanted us to all move in, and have a good time.”

bosses tease series finale || Check out series finale photos ||

’s timeline explained || Ginnifer Goodwin and Josh Dallas interview || Lana Parrilla interview || The Hot Seat || Colin O’Donoghue interview ||

‘s 25 craziest fairy-tale twists || Andrew J. West and Dania Ramirez interview || Rose Reynolds and Tiera Skovbye interview || Rebecca Mader interview || Jennifer Morrison interview ||

Alas, viewers didn’t get too much of a happy ending for Mader’s Zelena, a.k.a. the Wicked Witch. During the 150th episode, the future Zelena — let’s just call her that, okay? The timeline is wonky! — got her happy ending with Chad (Kip Pardue), whom her cursed counterpart Kelly West was set to marry. However, we didn’t actually see their wedding. The Zelena viewers saw in the finale is the past Zelena, whose child Robin is still 5 years old in her time. (Don’t try to figure out what the combined realms mean for the timeline, it’s fine. It’ll just make your head hurt.)

Still, Mader didn’t mind not getting finality with the character — after all, she already has a spin-off idea in mind. “Really, to me, the finale isn’t about what happens to Zelena, it’s more about the Evil Queen becoming the Good Queen, which was the journey of the show,” she says. “I’m just a big fan of Lana’s character. To go from being the Evil Queen to the Good Queen in that coronation that we did, I just think is a pretty spectacular 180.”

Read our postmortem with executive producers Adam Horowitz and Edward Kitsis here, find out how Lana Parrilla reacted to Regina’s ending here, see how Colin O’Donoghue felt about that heartbreaking ending with Hook and Rumple here, and get the scoop on Alice and Robin’s unfinished story here.