Several Japanese actors when approached immediately turned down any suggestion about appearing in the film. The Nanking massacre still touches a raw nerve in Japan today and for some Japanese actors the thought of appearing in a film about it was beyond comprehension.
One of the chief headaches for the production involved the scene where a Japanese soldier insists on searching the girls' dormitory in the college and orders the girls to remove their nightgowns. A huge majority of Chinese actresses refused to appear nude because it would have brought shame to their families.
Shanghai doubled up for Nanking in 1937. Although Shanghai is an ultra-modern city, it also has many pockets of underdeveloped real estate that have barely changed from the war years.
Fortuitously, a lot of 30s style housing was earmarked for demolition by the Shanghai authorities to make way for new skyscrapers. The production was able to use these leveled areas to represent the aftermath of bombing raids.
The movie was severely panned in Japan. where the Nanking Massacre is still an issue and muddles the relationship with China to this day. Particularly, nationalists objected the clear intervention of Prince Yasuhiko Asaka, who was by all intents and purposes not only aware of the massacre, but actively ordering parts of it. Asaka was given immunity as a member of the Imperial family by General Douglas Mac Arthur during the US occupation of Japan, and while he had his possessions confiscated and later stripped of titles and banned from holding public office, Asaka lived a respected and comfortable life as a commoner after the war, converted to Catholicism and died of natural causes at age 93, without ever being held accountable of his actions.