MIAMI - Three is the hardest number. Francis Coppola tripped on it ("The Godfather Part III"). So did George Lucas ("Return of the Jedi") and David Fincher ("Alien 3") and Sam Raimi ("Spider-Man 3") and the Wachowski brothers ("The Matrix Revolutions"). Peter Jackson pulled it off with "The Lord of the Rings," but all of those movies came from the same book and were shot back-to-back.