Too Hop to Handle (1956)

Sylvester Cat scoffs at his son's idea that a pipe like that of "The Pied Piper of Hamelin" could lure mice into their home to catch. But when Junior tries it and Hippety Hopper, the baby kangaroo, comes along, Sylvester believes in the power of the pipe and that Hippety is a giant mouse. The usual hijinks ensue, with Sylvester landing at the bottom of a well.