The film has autobiographical elements. When Hayao Miyazaki and his brothers were young, their mother endured nine years of spinal tuberculosis and spent much time in hospitals. Although not explicitly shown, it is suggested that Satsuki and Mei's mother also had tuberculosis, as she was hospitalized in a sanatorium, leading the family to move to the countryside. He mentioned that it would have been too painful for him to create the film if the main characters had been boys instead of girls.
The names of the two girls, Satsuki and Mei, are connected to the month of May. "Satsuki" is an old Japanese word for May, while "Mei" is the Japanese way of pronouncing the English word "May".
(at around 37 mins) The forest creatures and main characters in this movie got their names when Mei, the young girl who first sees them, mispronounces the word "troll." In the original Japanese version, when Satsuki first finds Mei sleeping in the grove behind their house, Mei tells her sister that she saw a "Totoro." Satsuki replies, "Totoro, do you mean troll, from the storybook?" and Mei nods in agreement. This part of the story was left out of the 1993 Fox English version, probably because the difference between "to-ro-ru" (the Japanese pronunciation of "troll") and "to-to-ro" would have been lost on English-speaking audiences. The quote appears in the 2006 Disney English version.
The movie initially did not do well at the box office and did not break even until about two years after the release when stuffed dolls based on the King Totoro character hit the shelves.
On its original theatrical release in Japan, it was double-featured with Le Tombeau des lucioles (1988), as the film was believed to be too big a financial risk as a standalone release.
Hayao Miyazaki: [flying devices] (at around 47 mins) Kanta is seen playing with the model of an airplane.
Hayao Miyazaki: [flying] (at around 59 mins) The Totoros fly on the top with Satsuki and Mei during the tree scene.