Gong Li was originally supposed to play Zhang Ziyi's part. Due to scheduling conflicts, the role was passed onto Zhang Ziyi and she gladly accepted because she thought the character was so interesting.
Both 'Li Gong (I)' and Maggie Cheung were originally considered playing the queen's role. When Ziyi Zhang took over the part, the script was rewritten to make the character younger.
What are the differences between the Chinese Version and the original Hong Kong Version?
A
In the Chinese Version several violent scenes were trimmed plus some erotic ones had to be cut as well. A detailed comparison between both versions with pictures can be found here.