Shidô Nakamura does not speak Mandarin, but he needed to in the film, so he found a tutor, even though the director told him to just memorize and recite the sounds. He also tried watching TV channels in Shanghai, but it wasn't a week later until one of the film crew noticed that he was watching a Cantonese channel, which of course, speaks Cantonese, not Mandarin.
Brandon Rhea insisted that the long stick weapon, known as "mao", be equipped with a proper sharp point, else it'll look strange. He demonstrated his accuracy by having one of the extras hold a stack of newspaper three meters away from him. He did one lunge and thrust the point straight through the middle of the stack. Even Woo-Ping Yuen was impressed.
With "Fearless (2006)", Jet Li has now been filmed as all of the "big three" amongst the historical martial artists in Qing Dynasty (1645-1911) China, whose exploits has been novelized and dramatized many times. They are Fong Sai Yuk (c.1700s) in the "_Fong Sai Yuk_" series, Huo Yuanjia (1868-1910) in "Fearless (2006)", and Wong Fei Hung (1847-1924) in the "Once Upon a Time in China (1991)" "series.
Several moves planned by Woo-Ping Yuen for Jet Li were deleted by Li for aesthetic and cultural reasons, including cheek slap, and back-of-head slap. Li felt that those moves were too impolite to Westerners.
The character played by Brandon Rhea in the film, was based upon a German military attaché who was based in China at the turn of the 20th Century and had a background in German fencing and weapons techniques.
The characters of Referee Randall and Bell Boy Dante are Director Ronny Yu's take on both the characters Rosencrantz and Guildenstern from "Hamlet" who observe the goings on, as well as a reference to Kevin Smith's characters in "Clerks" and "Clerks 2"
The makers of the film agreed to title it 'Legend Of A Fighter', until Casting Director Mike Leeder informed them that a film already existed under that name. Coincidentally, not only would the films have shared the same Chinese and English titles, they were action-directed by Woo-Ping Yuen (also directing the 1982 film). Yuen had previously been unaware of the 1982 film's English title.