Carmen was an Earth opera that Oswin Oswald enjoyed. The Eleventh Doctor called it a "lovely show". An aria from it, "L'amour est un oiseau rebelle", played in the Parliament of the Daleks as a signal sent from Oswin's imaginary room aboard the starship Alaska. (TV: Asylum of the Daleks)
In 1906, Mr Caruso did a production of Carmen in San Francisco, which affected ticket sales for Charles Virgil McLean's production of King Lear. (AUDIO: The Gift)
While searching for Clara Oswald and Bentley, who had been kidnapped in the Prison, the Twelfth Doctor hummed "The Entry Of The Toreadors". This tune was recognised by the Governor. (PROSE: The Blood Cell)