Lucasfilm screwed up. It's been rewritten since, but the title was Revenge of the Jedi, but Lucasfilm was flooded with mail saying that Jedi don't take revenge. Therefore it was changed, after the marketing started. Lucasfilm spun it so that it seemed that it was always their intention to have it be "Return."
Going off-topic for a second, but that's one of the key things that bugs the living **** out of me concerning the SW films: Lucas and LFL's insistence that everything was always intended to be exactly the way it turned out, and that stories to the contrary are just rumors and fan-created legend. Between the whole "there were never going to be 9 episodes, only 6 episodes" mantra, and the "I had this all planned out from the beginning" nonsense, I sometimes wonder if ol' George hasn't gone senile a little early. I guess when you have an army of "yes-men" surrounding you, it's easy to lose touch with reality.
In the new "Art of the Clone Wars" book, Lucas claims in the Foreword that he always
had intended the Clone Wars to be between Jedi/Clones and an army of Battle Droids.
In honor of George Lucas, I'm henceforth claiming that I always planned for my life to be a series of catastrophic emotional failures, and that any claims to the contrary are fanboy delusion.