Polley won her Academy Award for Women Talking, starring Claire Foy, Jessie Buckley, Ben Whishaw and Frances McDormand, in Los Angeles last month.
The 44-year-old shared on Twitter a letter she received on April Fools Day purportedly from the academy, which read: “We say this to you with the deepest regrets: the Oscar you received was given by mistake, you must return it.”
The letter said Polley had “one more week to enjoy it” but then she must “mail it back to LA where we will give it to the rightful best adapted screenplay, All Quiet On The Western Front”.
It continued: “We are sorry for your loss, but it is only fair that the play with the real best adapted screenplay gets the Oscar.”
The letter also said the film academy had realised its mistake on the night of the ceremony but wanted to avoid another “fiasco”, referencing La La Land being named winner of best picture during the 2017 ceremony instead of Moonlight.
It was signed in a childish hand purporting to be from David Rubin, the president of the Academy of Motion Picture Arts and Sciences.
Polley tweeted a photo of the letter, captioning it: “My 11-year-old swung low for April Fools Day this year.”
The director of All Quiet On The Western Front, Edward Berger, also played along with the prank on Twitter.
He wrote: “Dear Sarah, to save on mailing costs as I live overseas the academy has asked me to provide you with my address so you can ship the Oscar directly. I will follow up shortly. Ok with you? All best, Edward.”
Polley replied: “My kid says to tell you that it’s already packaged and on its way.”
Berger added: “Thank you. Tracking number please. Would hate for it to get lost.”
All Quiet On The Western Front won four Oscars in March, including best international feature film, from nine nominations.
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