The glaring gaffe was not lost on eagle-eyed viewers, who promptly expressed their disbelief on social media.
Taking to Twitter, one wrote: "So this is where we're at now! A Starbucks cup!"
While others were more vocal: “You’re telling me they had TWO YEARS to put together a decent show and they couldn’t even spot the goddamn Starbucks cup in Winterfell??!?!”
Another fan thought product placement on the show had taken a turn for the worse: “Wow. Product placement negotiations are getting fierce!”
While another joked: “If that’s Dany’s Starbucks coffee I feel bad for the barista who has to write her name on the cup.... hand must be cramping.”
The cock up comes as season eight gears up for a dramatic climax at Kings Landing over the course of its final two episodes, with the finale episode on May 19.