Where besides opera would you be so unable to predict what you will see? So why exactly are these people wearing what look like French Farthingales in a production of Mozart's Mitridate, Re di Ponto? Men playing men, women playing women and women playing men--all are wearing them in an opera first performed in 1770. The style, worn by women, died out c. 1600. And the drama takes place in 63 bc.
Mitridate, King of Pontus and other kingdoms, in love with Aspasia (tenor-played by a man--Bruce Ford)
Aspasia, betrothed to Mitridate and already declared Queen (soprano-Luba Organasova)
Sifare, son of Mitridate and Stratonica, in love with Aspasia (male soprano-played by a woman-Ann Murray)
Farnace, eldest son of Mitridate, also in love with Aspasia (male alto-played by a man-Jochen Kowalski)
Ismene, daughter of the King of the Parthians, in love with Farnace (soprano-Lillian Watson)
Marzio, Roman Tribune, friend of Farnace (tenor-Justin Lavender)
Arbate, Governor of Nymphæa (male soprano-played by a woman-Jacquelyn Fugelle)
The most interesting thing about this opera is that it was written by Mozart when he was 14. It is a fully realized opera seria in a style that I would call rococo. Every bit of it is recognizably Mozart. He shows no interest in the Gluck reform movement going on then and composes roles for castrati in formal set-piece arias. Mozart grows up into a more sophisticated composer, but so does the world generally. He is completely in tune with his era.
The singing is lovely, and the vocal writing is amazing. Try to ignore the incongruous costumes.
This opera makes clear all the problems of opera seria. From a theatrical perspective it is too static and meditative for modern life. Nothing lifts this from the surrounding repertoire except that it is by Mozart at 14. If you're curious, definitely look it over. If you want to be entertained, it will not do at all.