That song was first recorded in 1931.
Edith's wall calendar is also out of date by several years. IIRC, David R George III covered this in his "Crucible" novel, explaining that Edith had deliberately stopped turning pages on it when her father passed away.
it's a wonder that the "1930" which Kirk visited was even close to the real thing.
Floyd's barbershop from Mayberry even swapped location.