Ted Cassidy's cameo appearance as Lurch is heralded by the theme from The Addams Family (1964) played on the harpsichord.
This episode is based on a story that was published in issue #36 of the Batman comic book, dated August/September 1946.
Throughout the series, some of the regular villains have various multiple encounters with Alfred. However, whenever Alfred poses as a different identity doing undercover work for Batman, he is never recognized by villains from previous encounters. An exception to this Season Two's "The Penguin's Nest" where Alfred poses as a counterfeiter and is recognized by the Penguin.
This was actually the first set of episodes produced for the second season. With the Penguin having been featured in the last episode of the first season, it was decided to hold off on airing the episodes until later in season two.