In 1977, NBC gave its daytime hit "The Gong Show" a one-time-only shot in primetime. My guess is that Chuck Barris and crew filmed about an hour and a half of material for the show and cut it down to an hour's running time. There are extra disclaimers at the end of the show heralding this.
Big show with lots of people, in the filmed intros and on stage. You want music? (Alice Cooper, the UCLA band, Harry James and his orchestra) Comedy? (Rindercella, Tony Randall, the Bait Brothers) Action? (there's a crew fight) This show has it all. I am embedding the first part and you can find the rest yourself by clicking through to the YouTube page.