"SNL50: The Homecoming Concert" romped at Radio City Music Hall Friday. Inside the musical bash featuring Cher, Lady Gaga, Nirvana and many more.

Cher belted “If I Could Turn Back Time.” Lady Gaga performed her hit “Shallow.” Miley Cyrus sang “Flowers” and Lauryn Hill delighted the crowd with “Killing Me Softly.”

One-time-only collaborations included Bonnie Raitt and Chris Martin. Arcade Fire, David Byrne, Post Malone and Nirvana.

As luck would have it, Kevin Costner got seated next to Cher two days after he was in awe over her performance at the “SNL” concert.

Kevin Costner got close to Cher at the Saturday Night Live 50th anniversary show on Sunday, just days after he was caught gawking at her on stage. In pictures shared online, the recently divorced Yellowstone star appeared to be sitting side-by-side with the Grammy winner in the live audience at Studio 8H in New York City.

And, if we want to get really specific, one of our favorite moments was Cher's iconic performance...and Kevin Costner's reaction to it. At 78, the powerhouse singer gave a thrilling performance of "If I Could Turn Back Time" at Radio City Music Hall.