This is the first of two appearances Arlene Martel makes in the series, each time playing a different role. She is perhaps best remembered for her role as T'Pring, Mr. Spock's betrothed, in Amok Time (1967) from Star Trek (1966).
Gene Lyons and Arlene Martel not only appear in this episode of The Untouchables (1959), but also share the distinction of appearing in the TV series Star Trek (1966), albeit in separate episodes. Gene Lyons appears as Ambassador Fox in A Taste of Armageddon (1967) and Arlene Martel appears as T'Pring in Amok Time (1967).
This is the second of five appearances Cyril Delevanti makes in this series, each time playing a bit part as an attendant of some kind, flop house, men's room, newsstand, etc.