The previously unnoticed erroneous prop has even scored itself its own Twitter page, with a clever fan mock-editing the film's IMDB page to give the water bottle a shout out.
And the tweets didn't stop there.
The Greta Gerwig-directed film, starring Saoirse Ronan, Florence Pugh, Emma Watson and Laura Dern, came out in December 2019, and was made with a budget of US$40 million.
It scored the Oscar in February for Best Costume Design, given the authenticity and flair with which each character was styled.
It scored five other nominations, including Best Adapted Screenplay - won by Taika Waititi's Jojo Rabbit.
The hydro flask gaffe echoes last year's infamous rogue Starbucks cup that was spotted by Game of Thrones viewers, promptly sending the internet into overdrive.
Fans have wasted no time in making the connection with a series of hilarious memes posted to Twitter.
Responding to Starbucks-gate last year, actors from the hit series threw accusations around for months, making light of the rather embarrassing oversight.
Emilia Clarke, 33, who portrayed Daenerys Targaryen, claimed her co-star Conleth Hill was the culprit.
"We had a party before the Emmys recently, and Conleth, who plays Varys, who's 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'," the star told Jimmy Fallon on The Tonight Show recently.
Hill denied Clark's accusations on Britain's Channel 4, saying, "You know, there's no proof that I did it. So accuse away."
He told the broadcaster he would have needed "Mr Man arms," in reference to a British children's book character who had very long arms, to be able to plant the paper cup.
"I took a bullet for Emilia Clarke, and she touted me," Hill, 54, joked. "I'm just not making any comments until I have a lawyer."
Hill wasn't the only GoT star caught in the crosshairs.
Sophie Turner, who played Sansa Stark, pegged Kit Harington aka Jon Snow for the flub — apparently changing her tune after originally accusing Clarke.
Greta Gerwig, or anyone from the Little Women cast or crew, is yet to respond to the hydro flask-discovery.
