This is the second and final appearance of County Nurse Mary Simpson, played here by Sue Ane Langdon. She was previously played by Julie Adams, in the episode "The County Nurse."
Andy serenades Mary with the song "Red Rosy Bush." Later, in "Man in the Middle," he would sing the same song to Helen Crump.
A similar plot was enacted in season 4's "The Rumor." Barney jumps to the conclusion that Andy is engaged to Helen and he and Aunt Bee throw a surprise party.
Barney frequently refers to his new drum as a bongo drum. It's actually a conga drum.
The lake seen in the background at the end of the episode is obviously an enlarged photograph of a lake. The water never moves.