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.
Not surprisingly, none of the major film companies in Japan were interested in investing - or indeed screening - the film.