I remember when the trades formally announced that Liam Neeson would be starring in Batman Begins
... they announced him as Ra's al Ghul. Then, not even a day later, the trades (I think it was Variety or the Hollywood Reporter) corrected themselves and said Neeson was actually playing Ducard, much to the chagrin of fans everywhere.
Of course, this led to speculation that Neeson could actually be Ra's and that his Ducard persona was only a decoy, essentially ruining the "twist" of the film. It didn't quite matter, though, since the script for the film leaked anyway and any sort of secrecy that Nolan and Goyer were planning went right out of the window. I just found it funny how the casting process essentially spoiled the third act of the movie.