The Avengers director adapted, cast, directed and filmed a movie version of Much Ado About Nothing entirely in secret, reports The Wrap.
A website launched on Sunday night was the first announcement that the film had ever been in production, revealing that the movie "based on a play" has finished principal photography.
The cast includes many of Whedon's former collaborators, including Nathan Fillion (Firefly, Buffy the Vampire Slayer), Sean Maher (Firefly), Tom Lenk (Buffy the Vampire Slayer) and Amy Acker (Angel).
"Surprise! We just wrapped today..." wrote Maher on Twitter.
"I promise you it's the real deal and we're VERY excited about it!"
"Oh, it's real," Fillion added from his account. "Very. Very. Real."
Much Ado About Nothing is about the trials that face two pairs of lovers. While Benedick and Beatrice cannot stop confessing their love to one another, Claudio and Hero are shy and rendered practically speechless.
The independent film is yet to secure distribution.
> 'The Avengers' partially shot on iPhone