Judging from the calendar on the wall where Mannix enters and finds the security guard, this episode was filmed in December 1969.
Actor Larry Gelman makes a brief and uncredited appearance as an excitable journalist outside the hotel where Tom Corey (played by Garry Walberg) supposedly fell off of a balcony. Gelman and Walberg would be reunited the following season in the recurring roles of poker players Vinnie and Speed on The Odd Couple (1970).