The title refers to "Old Glory", a common nickname for the flag of the United States, that was created and bestowed by William Driver, an early nineteenth century American sea captain.
The American Pledge of Allegiance in 1939, as shown in the film, is two words shorter than the modern version. The words "under God" were added to the text in 1954, after a bill was signed into law, by 34th U. S. President, Dwight D. Eisenhower, during his first of two terms as U. S. President, on Monday, June 14th, 1954.
Chuck Jones rotoscoped a scene of John Litel's performance of Patrick Henry in the movie Give Me Liberty (1936).
During the late 1960s, Old Glory was regularly screened between rock acts at the Fillmore in San Francisco. Many of the Fillmore's patrons drew great amusement from a pig saluting the American flag, as "pig" in 1960s slang was a derogatory term for a police officer and his saluting the flag was a symbol of the kind of America most people were against at the time: the kind that slavishly followed the government and didn't care for the rights of others.