Starbucks owes a big thanks to "Game of Thrones." The company has reportedly received billions of dollars worth of free advertising after a scene in the HBO hit series accidentally featured what appeared to be a Starbucks cup last Sunday.

Though HBO has since edited it out in a new version that's currently available to watch on its streaming platform -- the original showed the cup situated in front of fictional character Daenerys, played by actress Emilia Clarke -- the error has given the coffee brand an estimated $2.3 billion in free advertising, Stacy Jones, the CEO of marketing company Hollywood Branded, told CNBC.

And the cup was not even from Starbucks. According to HBO, it was simply a craft services cup from a local coffee shop in Banbridge, Northern Ireland, near where the scene was filmed.

"This is a once-in-a-lifetime collision of opportunity for Starbucks," Jones said. "But really, this is just the tip of the iceberg, because what isn't being monitored or estimated is the word of mouth and social media on top of this."

Starbucks, of course, reacted to the media frenzy, tweeting on Monday, "TBH we’re surprised she didn’t order a Dragon Drink."

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A Starbucks coffee cup is seen outside a Starbucks Coffee shop in Washington, D.C., April 17, 2018. SAUL LOEB/AFP/Getty Images
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