This same helicopter was used in the chase scenes for the movie "Vanishing Point" (1971)
Dawn Wells' co-star, Russell Johnson, appeared in an earlier FBI episode titled "Ceasar's Wife.
Inspector Lew Erskine goes undercover as a magazine writer. His alias is Lee Rogers.
This was the last appearance for British actor Michael Rennie.
The uniform appears to be correct except that the "Major" does not have a name tag on the uniform.
Continuity error: When Inspector Erskine and Agent Colby interviewed Mr. Post at a gas station he works at, they have a light blue 1968 Ford Galaxie 500 4-door sedan and when they go to interview Dan Scott from the information they obtained from Mr. Post, the car is a 1969 light blue Ford Galaxie 500 4-door sedan.
Susan Strasberg was the daughter of actor and founder of method acting classes founder Lee Strasberg.
In the end credits. Inspector Erskine drives a Gulfstream Aqua colored 1969 Ford Mustang Convertible in the end credits. This would be the last time he would drive a Ford Mustang or a convertible in the end credits.