1.Diana Jones had no input in film, though she did meet with representatives from Studio Ghibli. She has been quoted to say about the film, “It’s fantastic. No. I have no input – I write books, not films. Yes, it will be different from the book. In fact it’s likely to be very different. But that’s as it should be. It will still be a fantastic film”.
2-Miyazaki personally travelled to UK to give private viewing to Diana Jones (author of the book) before the English version of Howl’s Moving Castle was released.
3-Howl moving castle was originally planned to be directed by Mamoru Hosoda, so he was invited by studio ghibli to make the movie, but he didn’t complete the movie because studio Ghibli executives rejected many of his concept ideas, and miyazaki took over, so it’s safe to say that howl’s moving castle was directed by both of them i guess.
4–Howl’s castle don’t make noise when it moves because, Miyazaki decided that the castle would be made out of papier-mâché, inside the castle you ill only find he living room, Howl’s room, Markl’s room, the bathroom, and the toilet. The huge appearance makes it intimidating, so that people can run away from the witch.
5-In the Japanese version of the film, Chieko Baisho is playing both Sophie’s 18-year-old self and 90-year-old self, while in the english version it’s split, the reason why miyazaki insisted on cheiko playing both role is to him even though sophie’s appearance changes her thoughts and emotions don’t.
6-Upon seeing Spirited Away, Christian Bale immediately agreed to play any role given to him by Studio Ghibli for Howl’s Moving Castle.
7-The design of the city Sophie lives in was inspired by Colmar, France