I believe the film that Arr1on mentioned was "Foul Play" with Chevy
Chase and Goldie Hawn
Chariots of Fire
The guys attend a performance of The Mikado
It Happened in Brooklyn
Has a charming scene in which Katherine Grayson plays a music
teacher/aspiring opera singer who dreams herself into the title role of
Perhaps the most notorious opera in a movie scene of all time.
Glenn Close gets her comeuppance at the opera
Glenn Close as a diva in a performance of Tannhauser
Ellen Barkin plays a wacked out diva who hires guard dog specialist Jack
Nicholson (movie has a bizarre twist ending involving a performance of
the Bach B Minor Mass)
The Red Shoes
While more of a dance film, it does have the young Norma Shearer (in her
film debut) torn between a struggling young composer premiering his
first opera and a tyranical dance impresario.
Julie Andrews (in male drag) attends Madama Butterfly with James
While this is a t.v. series it does have several operatic moments, most
notably (and hilariously) involving the family attending a performance
of Carmen sung in Russian!
Pavarotti plays a nervous tenor in a new production of Turandot.