Joseph Schmidt was arrested in 1940 in La Bourboule, not in Monte Carlo, as suggested in the movie.
Joseph Schmidt's escape to Switzerland is portrayed incorrectly. Unlike in the movie Joseph Schmidt passed the border of Switzerland in the night over a river and alone. He arrived there in a weakly status. In Switzerland he was considered an illegal alien and a work permission was refused. Inbetween he was in a hospital in Zurich.
Joseph Schmidt's manager was his uncle Leo Engel, not Max Himmel, as shown in the movie.
Joseph Schmidt released his song "Frag nicht" on the 2nd May 1933, before the premiere of Ein Lied geht um die Welt (1933) on the 9th May 1933. In the movie he recorded the song after the premiere.
Joseph Schmidt's tour around the USA including his performance at Carnegie-Hall was in 1937, while in the movie it was after the "Anschluss" in 1938.
Joseph Schmidt mentioned that he and Peter Schlange are in the asylum camp Girenbad for two months. In real life he came there on 6th/7th October 1942 and he died on the 16th November of the same year.