Actor-Inspired Element: The "Dark Master" name was chosen by AnnaSophia Robb. Early in production it was known as the Key Monster.
The Cast Showoff: Zooey Deschanel plays a music teacher when she was in a band in real life and is a professionally trained singer. AnnaSophia Robb plays with this, as she does have a song - but it's in the credits.
Creator Backlash: A variation. Filmmakers were not happy with the studio marketing the film as a fantasy adventure. The screenwriter was the author's son and the partial inspiration for Jess no less.
Non-Singing Voice: Josh Hutcherson claimed his singing voice is terrible, and the extras in the classroom were all New Zealand children - so their singing was dubbed in post production. It's credited as "Zoey Deschanel and the Terabithia choir."
Leslie was almost Spared by the Adaptation before the film was made, since several studios wouldn't touch the project because of the death. It was suggested that the character have a mild accident or be left in a coma instead.
An oppossum was meant to be trapped in the greenhouse, but they are not native to New Zealand and the production was not allowed to import one. So it was changed to a Common Brushtail Possum instead.
Allison Krauss was hired to score the film but she backed out and was replaced by Aaron Zigman.
Write Who You Know: The characters and story are based off events and people from Katherine Paterson's own life - Jesse off her son David, Leslie off his best friend Lisa Hill, etc., and Jesse's loneliness reflects Paterson's own inability to fit in at school with others. Plus the poverty of the situation during the Seventies post the Vietnam War era. And the religious connotations off her own upbringing, since she learned from her father (a missionary who often traveled as part of his duties).