The large white sedan that figures prominently in the second half of the story is a Checker Marathon. Better known as a taxicab, it was also available as a private vehicle. Because of its somewhat stolid appearance, it was often used in productions set behind the Iron Curtain.
This marks the first appearance of the Flying Sub in the series, not including the freeze frame under the end credits of the prior episode.
The music, visuals, plot and spy devices (aqualung cigarettes, e.g.) are all quite reminiscent of the popular James Bond films of the day.
The Soviet police car that picks up Admiral Nelson early in the story is actually a third generation Toyota Corona. This was the first Toyota passenger car to be exported to the United States in large numbers, but in 1965 it was rare enough to pass as a Russian vehicle.
A text overlay at the beginning of the episode indicates that it takes place in 1974.