The literal translation of the German title is "The Warrior and the Empress". The name of the main female character, "Sissi", refers to the nickname of Elisabeth, Empress of Austria and Queen of Hungary (1837-1898). There are several movies and television shows about the Empress Elisabeth, some with "Sissi" in the title.
The German title "Der Krieger und die Kaiserin" translates as "The Warrior and the Empress", but Tykwer wanted the English title to be "The Princess and the Warrior" instead.
Shot in Wuppertal, Tom Tykwer's hometown.
According to Roger Ebert, "what's special about the film is at a deeper level, down where Tom Tykwer engages with the souls of his characters".