Sammy Davis Jr. performed the role of "The Caterpillar" discovered atop a giant mushroom in a flower garden. The Caterpillar slithers off the mushroom to the ground where Davis dances a soft shoe number. Producer Irwin Allen had insisted the dance area be the typical Hollywood Musical slick shiny gloss floor finish. Rehearsing on the slick floor, Davis slipped and demanded the floor be changed. Art Director Hub Braden had had this problem before with dancers not able to perform on similar studio floor finish. Construction Coordinator James F. Orendorff replaced the flooring surface with material that Braden requested. With it painted and dusted with sand, Davis performed his dancing segment perfectly, happy and grateful that the crew were quick to respond with his wishes.
When Alice grows in the court scene, she says "But I didn't eat any cake or mushroom!" That line was left behind from a deleted scene (based on a scene in the book) in which Alice ate the Caterpillar's mushroom which caused her to grow and shrink.
Sammy Davis Jr. (Caterpillar) also provided the voice of the Cheshire Cat in Alice in Wonderland or What's a Nice Kid Like You Doing in a Place Like This? (1966).