Dawn Wells (Mary Ann) was actually crowned Miss Nevada in 1959.
In the swimming scene on the beach, Mary Ann states to the Professor that she simply wants to beat Ginger & Mrs. Howell, not "Cassius Clay", (referencing the birth name of Muhammad Ali. This episode was done in 1964, around the time of Ali's controversial conversion & protest of the Vietnam War.)
In the swimming scene at the lagoon, as the Professor is explaining the benefit of isometric exercise, Mary Ann consents to do it as long as she doesn't end up looking like Johnny Weissmuller, referencing a former Olympic swimmer & later, an actor who portrayed Tarzan in early Hollywood movies.
Ginger's song "Let Me Entertain You" is from the 1959 Broadway musical Gypsy. It is all about the life of stripper Gypsy Rose Lee and her stage mother, Rose. Mary Ann's soft-shoe tap dance music "Tea for Two" is from the 1924 Broadway musical No, No, Nannette.
The second time a gorilla is seen on the island. First, #1.22; Diamonds Are An Apes Best Friend. Third, #2.11; Chain of Command. Fourth, #2.22; Forward March. Fifth, #3.20; Our Vines Have Tender Apes.