I loved that scene, too! If you go on the website, they actually have a still of that part up (it's in the Whoville section, I think).
When I was trying to convince my friend to come see it with me, I listed off the voice cast, and when I got to Carol Burnett, she had no clue who she was. My first thought when I heard that was, "If you don't know who Carol Burnett is, I don't think I can help you." (I didn't say that, though.)