Frank Gorshin was in a contract dispute with the producers and was replaced with John Astin in this episode.
The Riddler floods a bank so that he can raid the vault in scuba gear, a scheme he pulled in his very first comic book appearance in Detective Comics 140 (October 1948).
Ironically, John Astin here appears in the very TV show that was responsible for the cancellation of The Addams Family (1964).
Third actor from The Addams Family (1964-1966) tv series to appear in this series, the other ones being Carolyn Jones who appeared as Marsha, queen of diamonds and Ted Cassidy, making a guest "window" cameo appearing in character as Lurch.
This episode is notable for featuring the only "underwater" fight sequence of the series.