This was the "Excitable Boy" tour, with the band from the album (Waddy Wachtel on guitar, etc.). Warren had recently broken has leg after a fall off the stage in Chicago. He performed the show with a full leg cast. Through the first part of the concert, he sat dutifully (doctor's orders) at the piano. By the end of the show, he was jumping wildly around the stage. This is how he broke his leg in the first place.
Richard Belzer, at that time an unknown comic, performed a stand-up routine as the opeing act.