My other Muppet mistakes...
As a young kid, I believed that Jim Henson performed Beautiful Day Monster, not Frank Oz.
I thought Frazzle was performed by various Muppet performers. Now, I realized that only Jerry Nelson performed that orange, furry monster. Oops!
I believed that that the Grouch cop and the jail were performed by another puppeteer. Now, I found out it was Jerry Nelson, the same guy that not only did the grouches with his rough voice, he did Herry Monster, Sherlock Hemlock, and so much more.