Dr. Frank Stranges was the real-life founder of the National Investigations Committee on Unidentified Flying Objects (NICUFO), a California non-profit Corporation founded in July 1967.
The interview with real-life UFO expert Dr. Frank Stranges was not in the original script. While Dr. Stranges was visiting the UFO set during filming of "Ordeal" (two episodes after this one), the producers decided to film an interview with him and incorporate it into this episode, which was still in the editing process. There are also added scenes later in the episode with Cmdr. Straker (Ed Bishop) and Lt. Ford (Keith Alexander) reviewing this interview during a communications blackout.
The seventeenth episode broadcast, but the seventh to be filmed.
The original name of this episode was "Crater 236". This refers to the name of the crater containing the Alien device.
Lieutenant Keith Ford (Keith Alexander) is a former television interviewer who became a founding member of S.H.A.D.O. and its main communications officer. Alexander left the series after the production break between studios, only appearing on 15 episodes. Later in his career, he would appear as a newscaster on Superman (1978).