Completely Different Title: Played with. The Japanese title Mimi o Sumaseba (If you listen closely) and the English title "Whisper of the Heart" are two halves of the japanese saying "If you listen closely you can hear the whisper of the heart." Chibli studios selected the English title, which was used on merchandise in Japan prior to the Disney translation deal.
Defictionalization: The Cat Returns was pitched as a story, possibly the story, written by Shizuku. If it is Shizuku's story she rewrote it a lot while polishing it.