The Muppet Babies (Kermit, Piggy, Gonzo, Fozzy and company) live in a large nursery watched over by Nanny. The babies have active imaginations, and often embark upon adventures into imaginary worlds.

How’s that work? Well, basically, the answer is Jim Henson. He was so widely beloved in Hollywood that producers would just let him use their stuff, with a handshake agreement not to do anything ...