HOLLYWOOD -- It turns out that rumour about Brad Pitt saving Guy Ritchie's Sherlock Holmes movie by joining the cast as Holmes' arch-foe Moriarty, is just that.

So how did it get started in the first place?

Elementary, my dear reader.

When British tabloid the London Mirror had first reported that the big budget production had scheduled an additional 10 days of production -- even though it had wrapped long ago -- to shoot the fresh Pitt footage, the news spread like wildfire.

It actually made sense given Ritchie's track record.

After all, the last time the director diverted from his usual bad guy flicks, the result was that disastrous Swept Away remake starring his ex.

Then there was the fact that, after his triumphant career comeback last year with the back-to-back successes of both Iron Man and Tropic Thunder, Robert Downey Jr. lost a bit of momentum with The Soloist, the one-time Oscar hopeful which had received a lukewarm reception at best.

But the truth of the matter is, the London Mirror didn't necessarily fabricate the story, it just confused the facts.

Pitt actually did recently join the cast of a movie playing the part of Robert

Downey Jr.'s arch-foe. But it wasn't the cast of Sherlock Holmes.

It's Oobermind, a Dreamworks animated superhero satire for which Pitt's providing the voice of jaded crime-fighter MetroMan, and Downey Jr. was originally set to play the part of the diabolical title character, before scheduling conflicts forced him to drop out of the project.

He was replaced by Will Ferrell.

As for Sherlock Holmes, while it's true that Warner Bros. has ordered additional shooting days, that sort of stuff happens all the time when certain sequences require clarification or endings are altered.

The studio insists the movie will still open Christmas Day as originally planned.

So there you have it -- The Anatomy of a Rumour.

See what a little detective work can accomplish?

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