At 7:22 Samantha can be seen smoking a cigarette; the only time she does so in the show's entire eight years.
Samantha wears a dark wig appearing to look like Serena a year before her cousin makes her first appearance.
The actor who played Mr. Kravitz (George Tobias) was 16 years older than the actress who played Mrs. Kravitz (Alice Pearce).
Larry refers to Darrin as a "Son of a Gun" seven different times in this episode.
When Gladys interrupts her husband Abner while he's practicing his flute, the few notes of music heard are from an arrangement of the first (and justly famous) minuet from Mozart's Divertimento in D, K. 334, for strings & two horns.