This movie had been divided in two parts for the theatrical release in the Asian market. The American release will be the condensed version of these two parts. The reason given was that the Asian viewers are more familiar with the characters and their exploits while the western viewers might be confused with the numerous characters and their similar names (therefore keeping it simple for the US market).
Yun-Fat Chow was originally selected for the role of Zhou Yu, and had even earlier been considered for the role of Liu Bei. However, he pulled out just as shooting began. Chow explained that he received a revised script a week earlier and was not given sufficient time to prepare, but producer Terence Chang disputed this, saying that he could not work with Chow because the film's Hollywood insurer opposed 73 clauses in Chow's contract.
Ken Watanabe was originally selected for the role of Cao Cao. According to a report, some Chinese fans voiced objections over the choice as they felt that it was inappropriate for a Japanese actor to portray an important Chinese historical figure. The report claimed that the protests influenced the decision of John Woo, who eventually chose Fengyi Zhang for the role.
John Woo said that this film differed from other films based on the Three Kingdoms, including story-based dramas and San guo zhi jian long xie jia (2008), because it "brings out more humane stories tangled with the characters' psychology and life events."
John Woo: [Two Guns] In this case, it was two swords, as the movie takes place in 208 A.D. Zhou Yu and Prime Minister Cao Cao each hold a sword to the others throat in John Woo's trademark "Mexican Standoff" image.