1. Isao Takahata (director of The Tale of Princess Kaguya, Grave of the Fireflies, and My Neighbor the Yamadas) and Hayao Miyazaki (director of Spirited Away, Princess Mononoke, and My Neighbor Totoro) cofounded Studio Ghibli together. Takahata discovered both Miyazaki and Joe Hisaishi, the composer for many Studio Ghibli films.
2. Hisaishi was asked to re-score some of the music for the English release of Castle in the Sky. According to Disney, Ghibli's North American distributor, markets outside of Japan weren't comfortable with large gaps without music. In the original Castle in the Sky, there is only an hour of music in the 124-minute movie.
3. The films that Miyazaki directs are entirely in his vision. He storyboards everything himself and uses those images as a script. Production begins before the boarding finishes, so no one, including Miyazaki, knows how the film will end.