"Say, @henrycavill. Had a thought," the Mission Impossible director wrote.
"Curious if you're interested in a role in the 6th instalment of Mission: Impossible. No pressure."
Comments started pouring in from excited fans, asking for Cavill to accept.
"How can I say no to a man with such perfect hair," Cavill finally wrote, mocking a user's comment on McQuarrie's "perfect hair".
"Excellent. Just a few caveats," McQuarrie wrote.
"Must enjoy extreme heights, high speeds, motor vehicles of all varieties (especially aircraft), practical stunts, firearms, and sporadic exposition. All good?," he asked.
The Superman star said he would accept, but "only if I get to fly for real".
"I do believe I specified practical stunts. You in?," McQuarrie replied.
After Cavill finally writing "I'm in!", the director wrote: "Outstanding. Welcome aboard. Your social media account will self destruct in 5 seconds."
McQuarrie is known for directing most Tom Cruise-starred films since 2012's Jack Reacher.
He is currently working on Mission: Impossible 6, starring Rebecca Ferguson and Jeremy Renner.
Cavill has just finished shooting DC's Justice League alongside Ben Affleck and Gal Gadot, and has recently teased the appearance of the Green Lantern in the upcoming movie.
There is yet no information available as to what part the actor will play in the Mission Impossible task force, but the movie's villain has yet to be cast.
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