The Welsh star jetted to Oklahoma earlier this year (12) to visit McAdams on the set of the upcoming romantic drama and he was taken by surprise when director Terrence Malick roped him into shooting a few scenes as Ben Affleck's boss.
But Sheen's part has now been cut for artistic reasons.
He tells New York Magazine, ""I played Ben's boss, but that side of the film got cut down so much. I just went to visit my girlfriend Rachel on the set, and then Terry asked if I would do a day's filming on it, so I was like, 'Yeah, sure.' It was just that I was around, and at the end of the day, you know, it was only two scenes.
""The producer sent me a nice email just saying, 'This is what's happening...' But it wasn't like I had gone through the whole thing of auditioning for a Terry Malick film and then saying, 'Oh, I've got the part!' That's happened to me before - I've done films where a lot of it gets cut and then it's kind of really disappointing.""