I Haven't Got a Hat (1935)

Continuity mistake: Before Little Kitty attempts to recite "Mary Had a Little Lamb", you can see there is writing on the blackboard behind her. When she makes her exit, the writing has disappeared, and when Ham and Ex appear, the writing is back again.

Porky Pig: Listen, my children, and you shall hear 'The Midnight Ride of Paul Revere'.