Zelda Williams is Robin Williams' real-life daughter, who portrays his daughter in this movie. While Eleanor Columbus, who portrayed the other daughter, was Chris Columbus' daughter.
Frank Welker was the only actor who had previously been in a Dr. Seuss project, having played some characters in The Grinch Grinches the Cat in the Hat (1982).
Sir Patrick Stewart and Christopher Lloyd also appeared in Richard au pays des livres magiques (1994), which was released to theaters the same year this special premiered, but just a few weeks later.