First episode to feature BJ Hunnicut with a mustache. It is a joke mustache, drawn on for Kentucky Derby Day. He grows a real one at the start of Season 7, which he keeps for the rest of the series.
While Hawkeye, BJ and Radar are looking through the mail to see if there might be a letter addressed to the Inspector General, they find one from Cpl. Benson. Radar says he's OK, he's been there since June. Since it's Kentucky Derby time, the beginning of May, that means Benson has been there almost a year. Another case of a "permanently assigned" soldier that's never seen until a specific story line introduces him. Then that soldier is never seen again. In this case, it's because Col. Potter gets rid of him.