The song that Ashley O sings is a reworked version of Nine Inch Nails' "Head in a Hole," from 1989, with a few new lyrics more suitable to a bubblegum pop star. The song in the end credits is an actual cover of the song, performed by Cyrus.
"There's nothing worse than when you're watching a film or a TV show about someone who is meant to be a celebrity, be they a comedian or a musician or whatever, and you just don't believe that they would actually be very successful," Brooker told GQ of the worry over having to write a believably popular pop song. "I was just out for a run with Spotify playing, and some Nine Inch Nails came up. And I thought, You know what? You could turn this into bubblegum pop. You could turn this into dance pop if you tweaked it a bit."
Nine Inch Nails frontman Trent Reznor turned out to be a big Black Mirror fan and loved the idea, so he fully approved.