Mononoke means angry or vengeful spirit. Hime is the Japanese honorific word that means princess, which, in the rules of Japanese grammar, is placed after a person's name instead of before, as is the custom in many Western languages. When the film's title was translated into English, it was decided that Mononoke would be left as a name rather than translated literally. This also explains why Ashitaka mostly calls the princess by her real name 'San' instead of Mononoke.
Japanese mythology tells that dogs/wolves are always male-voiced, and cats are always female-voiced, regardless of sex. For this reason, a man, Akihiro Miwa provides the voice of Moro the mother wolf in the Japanese version. His casting is perhaps an in-joke to his career as a female impersonator. In the English dub, however, Moro is voiced by a woman (Gillian Anderson).
When it was announced that the Miramax/Buena Vista region-1 DVD would only contain the English-language dialogue track adapted by Neil Gaiman, there was enough fan protest to convince Miramax to delay the release in order to include the original Japanese-language dialogue.
Neil Gaiman, in Anglicizing the script, chose to simplify some plot elements to provide a cultural context for phrases and actions not well known outside of Japan. Specific terms like Jibashiri and Shishigami, for example, are changed to the more general Mercenary and Forest Spirit. On the English language DVD, the subtitle options have a literal translation of Hayao Miyazaki's script in addition to Gaiman's adaptation.
Disney/Miramax, which released the film in North America, was contractually obligated not to edit any footage out for its North American release. They asked to, but were refused. Although they kept their end of the bargain in not editing the film, they did release it into far fewer theaters than promised and expressed surprise that it had made little money at the box office.
Princess Mononoke was the first animated film ever to receive the Japan Academy Prize for picture of the year. Only one other animated film has ever received this award (Spirited Away (2001), 2002). Prior to 2007, there was no category for Best Animation of the Year, which was won by Toki o kakeru shôjo (2006) in its first year.
When Harvey Weinstein obtained the North-American distribution rights to Princess Mononoke, he approached director Hayao Miyazaki and insisted on a shorter version of the film that would be better attuned to American audiences. However, Miyazaki was still so upset by the heavily cut version of his Nausicaä of the Valley of the Wind (1984) (released as 'Warriors of the Wind') that he angrily left the meeting. Several days later, Studio Ghibli producer Toshio Suzuki sent a katana sword to Weinstein's office with 'NO CUTS' embedded into its blade. The film was later released in the USA in its uncut version. When asked about the incident in an interview, Miyazaki simply smiled and stated "I defeated him".
Many speculate that various things featured in the Nintendo game Zeruda no densetsu: Buresu obu za wairudo (2017) were greatly inspired by this film. For example, in the first 10 minutes of the film, the clothes Ashitaka is wearing closely resemble both look and color pallete of Link's tunic. Ashitaka has a sword, and also uses the bow and arrow as his main weapon, which are also the weapons Link uses in this game and the previous ones. Another example is the wooden observatory tower which is destroyed by the wild demon. It closely resembles a similar wooden tower with a ladder overlooking the land of Hyrule in Breath of the Wild. Other similarities include the villager's hats, wild monsters/demons, and simply the vastness of the land, similar to the "open world" concept of Breath of the Wild.
Contrary to what some may think, the English-language dialogue in the American version is not a direct translation from Japanese to English. One only has to turn on Literal Japanese-to-English translation subtitles on the region-1 DVD to see that dialogue was paraphrased into comfortable American English.
While "Princess Mononoke" was acquired after it was released in Japan, its American release was delayed for almost two years, allegedly because of a negative reception at a Saint Paul, Minnesota test screening.
The trivia item below may give away important plot points.
When Ashitaka intervenes in the fight between Lady Eboshi and San, Eboshi exclaims that she's tired of Ashitaka's cursed right armed, before shouting "let me just cut the damned thing OFF!" Later in the film Eboshi loses her right arm to Moro.