If you watch the documentary Being Elmo, the puppeteer Kevin Clash talks about having the opportunity to work on this movie, but he had to pass because he was working on two TV series at the time. I can't imagine how it would feel to let the chance to work with Jim Henson slip through your fingers.

Luckily, after this movie Jim Henson made Labyrinth, and Clash was given a second chance to work with him...which he obviously said yes to.