Dr. Krakauer, played by Phil Foster, and Oscar's secretary, Myrna Turner (played by Penny Marshall) would soon play father and daughter in the series, Laverne & Shirley (1976) (also created by her brother, Garry Marshall), beginning in 1976.
Felix (Tony Randall) affirming his friendship with Oscar (Jack Klugman) starts singing the show tune "Together, Wherever We Go" from the 1959 musical, Gypsy, music by Julie Styne, Lyrics by Stephen Sondheim. In the musical the song is performed by the character Mama Rose along with her daughter Louise and boyfriend Herbie. In the original broadway production, the character of Herbie was played by Jack Klugman.
Sadly, Jack Klugman developed an actual throat problem towards the last years of his life. The condition made his voice rougher and harder for him to pronounce words audibly, and was written into the script of the reunion TV Movie "The Odd Couple Together Again.", making the movie something of an inadvertent sequel to this episode.