In the scene during which Chihiro squashes the small worm like thing that inhabited Haku with her foot that, Kamaji tells Chihiro to "Cut the line!" Cutting the line is a Japanese good-luck charm performed by making a chopping gesture through another person's connected index fingers. This is done whenever someone is affected by some impurity. During footage of the dubbing process in the "Spirited Away" Nippon-TV Special, Rumi Hiiragi, playing Chihiro, was not aware of this concept and had it explained to her by Hayao Miyazaki. One of the sound engineers commented "The young don't know it these days."
In order to animate the scene where Chihiro force feeds Haku the medicine in his dragon form, Hayao Miyazaki had his animators study a dog's mouth as they fed it treats while a veterinarian held its lower jaw.
To do the voice of Chihiro's mother talking while eating, actress Yasuko Sawaguchi actually spoke the dialog (in the original Japanese-language version) while eating a piece of Kentucky Fried Chicken. Actress Lauren Holly did the same thing in the English version with an apple.
Chihiro's father drives a first-generation Audi A4 sedan. The level of detail included by the director includes the Audi's trademark "Quattro" four-wheel drive system when Chihiro's father decides to take the car in the forest. Along with the ABS (anti-lock brake system) which pushes the brake pedal back when Chihiro's father brakes hard seeing the statue.
Executive Producer John Lasseter of Pixar supervised the English-language dubbing of the film and tried to match the actors' English-language dialog with the mouth movements of the animated characters.
The song over the closing credits ("Itsumo Nando Demo"/"Always With Me") was intended for a Hayao Miyazaki film that was never made. Miyazaki played it relentlessly while making this film and decided to include it in the end credits.
In the English-language version, John Ratzenberger (Aogaeru) completely improvised the ditty he sings when he is extolling the virtues of the rich customer No-Face. ("Welcome the rich man, he's hard for you to miss...") The original script's song was "Welcome the rich man - he's pretty big, you see/so all bow down and get on bended knee."
The city that Chihiro and her parents are moving to at the beginning is the fictional city of Tochinoki along Route 21, just north of Nagoya. Tochinoki is also the name of an amusement park to the north of Tôkyô and a spa resort in the south of Japan. The large hill in their neighborhood where the dirt road begins is named Green Hill.
The trivia items below may give away important plot points.
The character No Face greatly resembles a silkworm, an important animal in Japanese culture. No face seems to have a white face and a mouth below it. Silkworms have markings that look like facial features, and their mouths are below these markings. Silkworms and No Face eat constantly and grow rapidly. At the end of the movie, No Face goes with Sen to visit Zeniba. No Face stays with Zeniba spinning silk.
A minor dubbing error causes Haku's name to be slurred. His actual given name in "Sen to Chihiro no kamikakushi" is Kohakunushi Nigihayami, while "Spirited Away" just refers to the Kohaku River, ignoring the rest of his name entirely, and therefore changing the meaning of his name drastically.
The kanji names of many of the characters provide clues to their identities: Yubaba - hot-water crone; Zeniba - money crone; Kaonashi - no face; Bô - young boy/child; Kamajii - kettle/boiler pot/old man; Chihiro - thousand fathoms or thousand searches; Sen - thousand (pronunciation of chi kanji when isolated).
Lines were added in the English-language-dubbed version that do not exist in the original version: when Sen says that Haku is a dragon after she sees her parents in the barn; and the last lines between Chihiro and her parents in the car at the end.