General Ludwig in Bavaria married the actress Henriette Mendel in 1859, two years before, as suggested in the movie (The scene happened before Lombardy separated from Austria in 1859).
When meeting Nene Franz Joseph asks why she is not married. In real life she was married to Prince Maximilian Anton von THurn und Taxis.
The previous movie ended in 1867 during the crowning of Elizabeth and Franz Joseph as king and queen of Hungary, Sissi is also titled as such during the movie. However in this sequel the loss of Lombardy and Veneto from Austrian Empire happened in 1859 and 1866.