There’s more flat in “Flat Hatting” than just the title of the cartoon. The character designs and settings in much of the cartoon are flat, a style that would carry on when the studio which made the cartoon changed its name in 1946 to United Productions of America and eventually started making theatrical shorts.
The show-off pilot who’s flat-hatting in the short buzzes past people and buildings in San Francisco. Here’s some of the artwork.
The internet can’t make up its mind when this cartoon was made. It was copyrighted in 1946 by United Film Productions, a name that would be changed later in the year. Leonard Maltin identifies the designer as Robert Osborne of the New Yorker. The director was John Hubley, though the cartoon bears no credits as it was made for the U.S. Navy and not theatres.