HBO has dry roasted itself after a coffee cup mistakenly appeared in episode four of the final series of Game of Thrones.

Eagle-eyed fans wasted no time in taking to social media after spotting the anachronism, which appeared onscreen for roughly two seconds in front of GoT character Daenerys Targaryen.

In response, HBO said: "The latte that appeared in the episode was a mistake. Daenerys had ordered an [sic] herbal tea."

US trade daily Variety received an email from the show's art director Hauke Richter which read: "Things can get forgotten on set. [The coffee cup error has been] so blown out of proportion [because] it has not happened with Thrones so far."

So the - ahem - takeaway from the hoopla is that mistakes are very rare - and there is no House Maxwell planned for Westeros.

Read our episode four review here.