A Nice Little Dinner Party - S1-E19
Continuity mistake: The train shown is pulled by four diesel locomotives, "A" unit leads with two "B" units sandwiched between a second "A" unit. When Mrs. Stevens pulls the emergency stop cord, which would not likely be on a long distance passenger train, the locomotive shown doing an emergency stop is a steam one. Not to mention that by the time of this episode steam engines were obsolete, and less likely to have been employed, especially in passenger service.
Answer: Telstar was an early communications satellite system. Darrin, in a particularly sexist manner reflective of this era, is saying that telling a secret to a woman means it is guaranteed to be "broadcasted" to multiple people.
raywest ★