When Justin Timberlake couldn't make Sunday's concert celebrating the music of the new Coen Brother's movie, "Inside Llewyn Davis," master of ceremonies John Goodman told the crowd Timberlake's understudy would perform instead.
Then he introduced Elvis Costello.
"Heaven knows when you think Justin, you think of me," Costello joked with the Town Hall crowd.
Then Costello introduced his understudy, famed music producer T-Bone Burnett.
Replete with his trademark glasses, Burnett performed rousing backup vocals on "Please, Mr Kennedy." Timberlake's character sings that song in the film about the New York folk music scene in the 1960s.
Burnett acted as the project's executive music producer, just as he did for the music from the Grammy-winning "O Brother, Where Art Thou."
Another Day, Another Time: Celebrating the Music of "Inside Llewyn Davis" included music inspired by the film from a host of folk artists, old and new. And the second half is insane."
Rudin was right on the mark as Jack White opened with a three-song set that was followed by one of the more inspiring performances of the night by Rhiannon Giddens that brought some of the crowd to its feet.
Standout performances included Decemberist's frontman Colin Meloy covering a song he thought was a ghost story, bringing out Joan Baez to perform "Joe Hill" with him. Baez performed the song at Woodstock.
Patti Smith covered "Babe, I'm Gonna Leave You," recorded in 1963 by Baez, and made famous to rock fans a decade later by Led Zeppelin.
Costello, Sands, and Mulligan backed by the Punch Brothers performed a spirited version of the traditional folk song, "500 Miles."
Celebrity guests included Glenn Close, Jesse Eisenberg and Paul Rudd.
"Inside LLewyn Davis" won the Grand Prix Award at the Cannes Film Festival, and made its US debut Saturday at the New York Film Festival. The soundtrack is available on November 12.
As for the show, Mumford and Mulligan, who's in the film, performed several times throughout the evening, though there was not a Mumford and Wife moment.
While not addressing his wife, the Mumford and Sons frontman did say the night had "so many OMG moments."