The film was an adaptation of the fourth novel in a pentalogy, or five-novel cycle, known in China as the Crane/Iron Pentalogy and written by noted wuxia (kung-fu) novelist Du Lu Wang. The novels are "Crane Frightens Kunlun," "Precious Sword, Golden Hairpin," "Sword's Force, Pearl's Shine," "Crouching Tiger, Hidden Dragon," and "Iron Knight, Silver Vase." Much of the story is not about Li Mu Bai and Yu Shu Lien; they are in fact secondary characters who only become important later in the series. When a comic book adaptation of the fourth book in the pentalogy was slated, illustrator Andy Seto rewatched the film to get inspiration for how to depict the fight scenes.
While Ziyi Zhang's character is obviously highly trained and skillful in martial arts, the actress herself never had any official martial arts training at all. Instead, she used her dance techniques to learn her moves in these scenes as if they were a dance rather than a fight (which, in terms of creating and filming them, is actually not that far from the truth).
The four main actors all spoke Mandarin, but with different accents. Yun-Fat Chow had a Cantonese accent, Michelle Yeoh had a Malaysian/English accent, Ziyi Zhang had a Beijing accent, and Chen Chang had a Taiwanese accent. Because of the difficulty some Chinese-speaking markets had with the voices, some markets actually had a dubbed version (into standard Mandarin) of the soundtrack.
Taiwanese-born Hong Kong actress Qi Shu was originally cast in Ziyi Zhang's role of Jen Yu and worked on the film for several weeks, until her agent pulled her from the movie to do a Pepsi commercial in Japan. She has since changed agents.
According to Yun-Fat Chow, he had to do twenty-eight takes of his first scene on the first day of shooting, because he had such difficulty speaking Mandarin. When asked in an interview with TIME Magazine how he felt about his Mandarin pronunciation, he replied, "It's awful."
Michelle Yeoh tore her ACL (anterior cruciate ligament) during the shooting of an early fighting sequence and had to be flown to the United States for knee surgery. She returned to the set at different times to film non-action scenes until her knee had recovered.
The film holds the record for the most Oscar nominations for a foreign language film along with Roma (2018) with 10 nominations. Additionally, it shares the record for most Oscar wins by a foreign language film with Fanny and Alexander (1982). Both films won four awards.
(At around 1 hour, 5 minutes) At the cave scene, Lo sings a song. This song is in one of the old Turkish languages (probably the Uyghur language), which still can be understood in today's Turkish language. It is something along the lines of, "...yiriliyorida, gordum su guzel kiz havar guni, ...bu guzel aylari, ey guzel kiz havali kiz." It means, "...while she was singing softly, I saw that beautiful girl when sun goes down, ...this beautiful months, You beautiful girl, cool girl."
The first draft of the screenplay said, "You will note in the script that none of the fight scenes are described, and I will just inform you now that they will be the greatest fight scenes ever in the history of cinema, period."
Michelle Yeoh did not speak Mandarin. The script was presented to her phonetically with help from Mandarin-speaking crew members. In fact, her Malaysian accent can be heard throughout. Yun-Fat Chow did speak Mandarin (his first language is Cantonese), but native Mandarin speakers thought his accent was strained and overdone.
According to old Taiwanese newspapers, there was a Taiwanese-speaking movie in 1959 called "Luo Xiao Hu and Yu Jiao Long," an earlier adaptation of Du Lu Wang's novel. The old newspapers noted that this version was also a martial arts film. The leading actress, Hsiao Yan-Chiou, was originally a traditional Taiwanese opera actress. After the movie was released, Hsiao married, leaving "Luo Xiao Hu and Yu Jiao Long" as her last movie. The film is thought to be no longer in existence now, and it seems to hold no connection with Ang Lee's "Wo Hu Cang Long," except for the adaptation source.
The Green Destiny Sword Li Mu Bai carries translates to Green Dark World Sword, a place where the dead go. The "Mu" in Li Mu Bai's name translates to a kind of positive jealousy or longing, as in wanting something but probably never getting it.
(At around 15 minutes) In the first night scene, Bo meets two night-watchmen who later give two knocks on clappers/rods, indicating that it was the second watch of the night. The first watch begins at 7 P.M., and each watch is two hours long, so it was after 9 P.M. when Jen first sneaks into Sir Te's residence. If the number of times the night-watchmen sounds the small cymbal/gong was shown, the audience would know more precisely what time it was between 9-11 P.M.
(At around 5 minutes) The stamped documents shown by Shu Lien to the guards at the city-gate before she enters Beijing shows the date "in the 43rd year of the reign of (Emperor) Qianlong, the sixth month, the eighth day," which is the year A.D. 1778, somewhere in June or July.
Director Ang Lee commented that originally, he did not wish for Shu Lien to wield the heavy two-handed straight sword against Jen. This was consistent within the movie, as Shu Lien indicates her preference of the "dao," the saber with a broad, curved blade, instead of the straight-bladed "jian," Li Mu Bai's weapon of choice. The Green Destiny is itself a jian.
(aA around 3 minutes) In the hall where Shu Lien first meets Li Mubai, there are two large sets of couplets hung on the wall behind them. The inner couplet reads, "(right) The Tall (Qiao) Tree spreads thousands of branches, but don't they have the same roots; (left) the Long (Yangtze) River flows into tens of thousand of distributaries, but all have the same source," and it is about maintaining harmony. The outer couplet reads, "(right) In Spring and Autumn sacrifices, follow the Ancient Sages' Rites and Customs; (left) Arraying Left and Right, trace One Family's Generations of Continuity," and it is about maintaining tradition.