The main thing I remember about the movie is that it's muuuuch darker. And has a song sung by an elf somewhere in there that I loved. Now I'm curious about the fan theories!

So the idea was that Hitomi was much older in the movie. There was already the idea that Gaea isn't another world, it was all an internal world of her own fantasies. And being older and closer to adulthood her fantasies had taken a darker turn, hence why the movie is in that place with that tone.