Synopsis by Hal Erickson
After reading Lewis Carroll's "Alice" books, Mickey Mouse falls asleep and experiences a Wonderland of dreams. In his visions, Mickey passes through a rather sticky-looking mirror, immediately encountering humanized furniture, an angry umbrella and a self-answering telephone. Eating a huge walnut, Mickey is suddenly enlarged, then miniaturized, allowing him to perform an Astaire-like dance routine atop a huge opera hat. This leads to a full-scale Busby Berkeley routine with a pack of dancing cards, during which Mickey incurring the wrath of the "Charles Laughton" King of Hearts by cutting a rug with the "Greta Garbo" Queen. Much more zaniness ensues ("Calling All Cards!") before Mickey awakens from his dream. In its own carefree way, Thru the Mirror frequently matches and even surpasses the similar animation in Disney's much-later cartoon feature Alice in Wonderland.