Magda Schneider, playing Sissi's mother Ludovika in all three parts of the Sissi trilogy, is Romy Schneider's real life mother.
Sissi met Franz Joseph at the age of 15, and was married at 16.
Sissi and Franz only had four children together; Sophie, Gisèle, Rodolphe and Marie-Valerie.
According to historical records, Empress Elisabeth spelled her nickname as "Sisi" with a single "S". Due to the popularity of the Sissi trilogy, several films and series about the Empress incorrectly spell her nickname as "Sissi" with a double "S". The first film to use the correct spelling of her nickname in the title was Sisi & I (2023).