Swedish actor Nils Asther played General Yen. Asian actors were never cast in lead roles in American productions at the time. Although multilingual, Asther did not speak Mandarin. However, he did use a Mandarin dialect for the part.
Chinese officials in Washington, D.C. complained about the depiction of the treatment of war prisoners in this film (which were toned down a bit) and some dehumanizing language about the Chinese people, such as "Human life is the cheapest thing in China," (which remains in the film).
Grace Zaring Stone and her husband and daughter were invited to visit the set on one day of filming. Zering later said she was impressed by the realism of the set but that the film was miscast and that Barbara Stanwyck was all wrong for the part of Megan.
The trivia item below may give away important plot points.
In the original script, General Yen decided, at the last minute, not to go through with his suicide. The ending seems to have been re-written to the one that appears in the film after the decision was made to cast Barbara Stanwyck as Megan.