Ruth Buzzi recently revealed that she was originally supposed to be the first guest on the show, but scheduling conflicts pushed her back to episode #4. The guest star on the first episode was Juliet Prowse.
Frank Oz performs Miss Piggy for most of the episode, but Richard Hunt performs her in the At the Dance sketch and in the Panel discussion.
The backstage plot involving the "Robot Frog" and the sketches "Robot Reflections" and "Robot in Love" all appear in "The Muppet Show Book", published by Harry N. Abrams, Inc in 1978. All of these sequences were entirely illustrated by Tudor Banus in the book.
The robot Kermit refers to "bouncing baby figs". The real Kermit would use the same line in outtakes for 'The Muppet Movie' a couple of years later.