Dustin Hoffman originated Mr. Magorium's hairdo, bushy eyebrows, and lisping vocals. According to Hoffman, when he first tried the voice out on writer-director Zach Helm and two of the producers, "they freaked".
Molly Mahoney and Edward Magorium start jumping on the mattresses on the count of "triscadecaphobia," the fear of the number thirteen.
Natalie Portman and Jason Bateman sympathized with ten-year-old Zach Mills, who had to "go to school" during breaks in filming throughout the day. Portman and Bateman each started their careers as children: Bateman started working on television as a preteen in the early 1980s, and Portman started acting in films as a preteen in the mid-1990s.
To the right of the Door of Rooms is a purple plaque for The Good Work Geisel Grandleformer (Prototype). Theodore Geisel, better known by his pen name Dr. Seuss, wrote There's a Wocket in My Pocket!, a list of arbitrarily introduced fantasy animals whose names rhyme with ordinary household objects. The rhymes in the book may be the inspiration for this movie's title.