Complex sentence: With the mice now gone for good, Porky graciously apologizes to Sylvester and thanks him for saving his life, but one leftover mouse (the executioner) pops out of the longcase clock with a mallet behind Sylvester.
Split into simpler sentences: With the mice now gone for good, Porky graciously apologizes to Sylvester and thanks him for saving his life. One leftover mouse (the executioner) pops out of the longcase clock with a mallet behind Sylvester.