The two "Batman" episodes featuring Liberace were also the two highest-rated shows of the series' original run (1966 - 68).
In this and the "Batman" episode which follows it ("The Dead Ringers"), guest villain 'Liberace' plays the dual role of evil twin brothers. In real life, 'Liberace' was the survivor of a pair of twins, the other being stillborn.
By every account, including those of Adam West and Burt Ward, Liberace was one of the most pleasant, cooperative guests the series ever had, playing all-request mini-concerts for cast and crew at the end of each day's taping. The only cavil, a minor one, was that he insisted upon using his own piano: he wouldn't trust anyone else's.
Chandell's three molls, Doe, Rae and Mimi, are named are the first three notes of the musical scales, do, re and mi.
The music played by the piano roll machine that threatens to perforate Batman and Robin is "The Stars and Stripes Forever," composed in 1896 by John Philip Sousa.