Sissi was sick with tuberculosis. She insisted on being send to Madera to recover. After noticing some improvements in her condition she was send back to Vienna where she became a lot worst and then was send to Corfu to recover. She would only come back two years later.
When Sissi got very sick, Helene, then pregnant with her second child, followed Sissi to Madera to stay by her side. The two sisters were very close. This was never shown in the movie.
Director Ernst Marischka was originally going to make a fourth installation to the trilogy, but actress Romy Schneider refused to play the title character any longer.
The line that Greek flower girl is telling to Oberst Böckl when he is trying to flirt with her is "Den katalavaíno", which is Greek for "I don't understand".
Final film of Uta Franz.