The 'Last Christmas' actress revealed to Jimmy Fallon which of her 'GoT' co-stars confessed to leaving the cup on set.
However, the most lasting mystery from the HBO fantasy has nothing to do with the show's plot or characters, but rather an errant mishap featuring a modern day coffee cup that ended up in one shot from the season's fourth episode, "The Last of the Starks."
GoT alum Emilia Clarke stopped by The Tonight Show on Wednesday, where she was promoting her upcoming holiday rom com Last Christmas, and she seemingly may have revealed to Jimmy Fallon the long-sought after secret about who was responsible for the gaff.
After shooting down remarks her former co-star, Sophie Turner, told Fallon that pinned the blame on Clarke, the actress said the anachronistic coffee cup in question actually belonged to co-star Conleth Hill.
"So here’s the truth," Clarke began. "We had a party before the Emmys, and Conleth, who plays Varys - - who was sitting next to me in that scene -- he pulls me aside and he's like, 'Emilia, I have got to tell you something, love. The coffee cup was mine.'"
"It was his! It was Conleth’s coffee cup! He said so," Clarke continued. "He said, 'I think it was, I am sorry, darling. I didn’t want to say anything because it seemed the heat was very much on you,' and I was like, 'What!?!'"
Apparently, with no one looking his way, Hill decided to let Clarke take the wrap. Which proved to be a bigger deal than any of them likely expected, considering people are still asking about it nearly six months after the episode aired. But Clarke says she's pretty sure Hill was the one behind the mistake heard 'round the internet.
"I think that's who did it, yeah," Clarke said. "I mean, he said it. He might have been drunk, but he said it."
Meanwhile, in other big Game of Thrones news, ET spoke with Clarke on Tuesday about the announcement that HBO has decided to scrap their planned GoT prequel series -- starring Naomi Watts -- which filmed its pilot over the summer.
"I'm not really too sure [what happened]," Clarke said of the show, which was set to take place thousands of years before the original series. "It's difficult to get stuff made. I wonder. Maybe it'll be reincarnated at some point, but if it wasn't meant to happen now, then I'm sure it's because they know that it wasn't going to be as perfect as it should have been."
Check out the video below to hear more.
Meanwhile, Clarke's new holiday rom com, Last Christmas -- co-starring Henry Golding, Emma Thompson and Michelle Yeoh -- opens in theaters Nov. 8.
The 'Game of Thrones' Series Finale Had Another Coffee Cup Moment -- This Time With a Water Bottle