"The Fortune Teller" operetta by composer Victor Herbert and the lyricist Harry B. Smith was first performed on Broadway in 1898. Cathy sings the "Gypsy Love Song" from that operetta.
Cathy tells Patty that $5 is a lot of money, which it probably was in 1964 when this episode first aired, because adjusted for inflation that amount would equal approximately $48 in the year 2022. Moreover, Richard's $200 Hi-Fi set would equal approximately $1,900.
Cathy likens Patty to Michel de Nostredame, who was a French physician and astrologer, best known for his book "Les Prophéties" that contains 942 quatrains of verse that purport to predict the future.
This is the first appearance Jane Buchanan makes in the series, this time playing one of Patty and Cathy's high school friends named Agnes. In the following episode, i.e. The Tycoons (1964)], she plays another of their high school friends named Mary.