The filmmaker is ready to step behind the camera once more to shoot the third installment of the spooky story, 21 years after directing the last film in the franchise in 1989.
All four of the original 1984 Ghostbusters - Murray, Dan Aykroyd, Harold Ramis and Ernie Hudson - have signed on to reprise their characters in the forthcoming project - but Reitman has urged fans not to believe everything they hear, because a lot of the other casting details are pure speculation.
He tells ComingSoon.net, "There is almost nothing that is accurate online about that film. There is nothing... I mean, all these stories... there has been a ton of stuff about casting, about who's in... None of it is true (sic)."
And the director reveals pleasing the Lost In Translation star with Aykroyd's finished script is top of his to-do list - although he warns they my face a little wait before they hear back from the actor.
Reitman says, "We have a really good script, but Bill Murray has to read it. He hasn't read it. There has been all kinds of chatter online about him reading it and not liking it. He has not read a thing. He's never read anything. And I just sent it to him. So we'll see. God knows how long that will take. But we'll see."
And screenwriters have made room for another high-profile original castmember in the new story - they want Sigourney Weaver to return as Dana Barrett.
Reitman reveals, "Sigourney Weaver has a role in this movie. All the original characters have parts. As well as a whole bunch of new characters.
"It's got a really good story, this one. Maybe the best of the whole series. I hope we get to do it."
Ghostbusters 3 is scheduled to hit cinemas in December 2012.