In the Japanese version, Yoko Honna sings "Country Road" and is a decent singer in real-life.
Likewise, in the English dub, real-life friends Brittany Snow and Ashley Tisdale get to sing "Country Road" at various points in the film.
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." Ghibli 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.
I Knew It: Fans correctly predicted that the film would be released in North America in the spring of 2006.
Real-Life Relative: Producer Toshio Suzuki's daughter Mamiko translated the lyrics of "Country Road" for the film.