'Downton Abbey' Makes Glaring Historical Error in Press Photo

Check out the photo and try to spot the mistake!

— -- "Downton Abbey" has released a series of new photos to promote season five, which is slated to premiere stateside in January.

But one stood out from the rest, for the wrong reason.

In a photo that's going viral, a modern-day water bottle is on the mantle behind the Earl of Grantham, played by Hugh Bonneville and Lady Edith Crawley (Laura Carmichael). The show takes place in the 1920s.

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PBS, the network that airs the series in the United States, has yet to respond to ABC News’ request for comment, and the photo has been removed from the network's website.

But fans, including Darren Bell, a British photographer, are having a field day with the image on social media, with some even wondering whether the snafu was a stunt for publicity.

"Oh dear. Someone left a waterbottle in this press photo from @DowntonAbbey," he wrote. "#PhotoFail"