James Tolkan, who enacts many characters during the series, recreates the character of FBI Special Agent Richard Wragg from the first entry in the series.
The "Stenophone" device was "played by" a pre-WWII Dictaphone machine and the "Stenophone" cylinders seen were actual pre-WWII Dictaphone wax cylinders. All Dictaphones manufactured after WWII used acetate (and later Mylar) "Dictabelts" instead of wax cylinders.