Gilbert sarcastically suggests that Sullivan, wanting to write a more serious opera, might try to collaborate with "Mr. Ibsen in Oslo." At the period in which the movie is set, the city was named Christiania.
During the performance, Katisha's kimono is wrapped incorrectly. All Kimono wrap from the right side of the body to the left (i.e. the right side folds over the left), but her kimono wraps from left to right. Every other character has her/his kimono wrapped correctly.
This well known quote from the film is a factual mistake: "If you wish to write a Grand Opera about a prostitute, dying of consumption in a garret, I suggest you contact Mr Ibsen in Oslo. I am sure he will be able to furnish you with something suitably dull". The city of Oslo got the name in 1925 - a long time after Ibsen's death in 1906. During Ibsen's lifetime, the capital of Norway was called Kristiania.