Even though the film was entirely produced by Hanna-Barbera, with the exception of "Castle Thunder" being heard a few times, none of Hanna-Barbera's famous sound effects show up in this film. This became more common with the company during the 1990s.
Mr. Moundshroud's full name is Carapace Clavicle Moundshroud.
In Bradbury's original book are eight children who meet Mr. Moundshroud. In the movie it was reduced to four.
Wally exclaims "oh my gosh!" 15 times throughout the movie.