Michael says Archie served in the Army and Archie corrects him saying Air Force. Archie served in WW2 in the Army Air Forces, so Michael was actually correct as the Air Force was not formed until after WW2. (Note: Archie did mention Air Corps later in the episode, which had been a division in the army during World War II).
Bobbi Jo mentions going to Germany, however, Germany did not exist at the time since the show was set before the fall of the Berlin Wall. (Note: Bobbi Jo did specifically mention West Germany).
Duke and Archie are supposed to be the same age (approximately) which would make them both about 48 at the time of this episode. Duke would be considerably over retirement age for the armed forces.
According to Edith, Bobbie Jo's visit will mark the "first time in twenty four years that Archie and Edith will not be sleeping in the same bed together." She seemed to have forgotten when Cousin Maude visited in a previous episode, Edith slept in the bedroom and Archie slept on the couch and when Edith had jury duty in a previous episode, she slept in a hotel without Archie and in a future episode (Archie The Gambler), she said that after a fight with Archie, she took Gloria when she was a little kid and left Archie and stayed at her mother's home. Not to mention the many times Archie stayed overnight at hotels during various conventions.