Trivia: Myrna Loy was originally meant to be cast as Empress Tsu Hzi, but was reportedly sick of doing "yellowface" roles. As such, Flora Robson got the part.
Trivia: The Chinese extras cast in this film were almost all Spanish residents, especially in Madrid. This was done to such an extreme extent that some Chinese restaurants and other Chinese-Spanish-owned businesses in the Madrid area especially were forced to close for a few days due to lack of personnel.