In an interview on National Public Radio's "Fresh Air," Chiwetel Ejiofor said that he thought he'd challenge David Mamet to a friendly sparring match (keeping in mind Mamet had been a practitioner of jiu-jitsu for some years compared to Ejiofor's training for a few months). They squared off, and Mamet stepped on Ejiofor's foot with all his weight. Ejiofor couldn't free his foot and was vulnerable to attack. Mamet said words to the effect that "This match is over."
Chiwetel Ejiofor trained for nearly three months before shooting, spending up to twelve hours daily (according to David Mamet) studying and practicing jiu-jitsu.
Ed O'Neill's practice of Brazilian Ju-Jitsu partially inspired writer-director David Mamet to write the movie. He was also on an episode of Silver Star (2006), which was produced by David Mamet.