The last time B.J. Hunnicut appears without his trademark mustache. Starting with Season 7, he has it for the remainder of the series.
BJ mentions once dating Esther Williams' stand-in, and claims he could kiss her for an hour at a time because she could hold her breath so long. Esther Williams was a former teenage swimming champion turned actress for whom MGM created a special subgenre, known as "Aqua Musicals," which included garish underwater musical sequences. Williams was often called "America's Mermaid," as it appeared that she could stay underwater forever.
First appearance of Hamilton Camp. He appears again in "The Moon Is Not Blue" (1982) in a different role, and finally in "Goodbye, Farewell, and Amen" (1983) as an announcer.
The title of this episode, "Major Topper," is actually a double pun. First, it refers to Major Charles Winchester's consistent ability to top his bunkmates' stories with his own experiences (i.e. Winchester offers a photograph proving that he once dated Audrey Hepburn, to counter B.J.'s claim that he once dated Esther Williams' stand-in). Also, it refers to the insane Corporal "Boots" Miller (Hamilton Camp), who is constantly shooting real bullets at invisible gliders and enemy prisoners that only he can see. In the movie Topper (1937), Cosmo Topper (Roland Young) is a bank president who interacts with ghosts that only he can see and hear, while everyone around him thinks he has gone insane.
The song Colonel Potter quotes in the beginning of the episode is "Dem Bones," aka "Dry Bones," a spiritual based on the Scripture from Ezekiel 37.