Yes, I recall that scene fairly well. Mork was caputured by some space villians, lead by Welch. Welch and her two hot lady henchmen were interrogating Mork. He was actually standing up when Rachel orders, "Tickle him!" Then the two female henchmen go down his body with a feather I think. He made some goofy sounds and that was it.
It really wasn't such a great scene. The best part of it was hearing Rachel Welch yell "Tickle him!"