The large white chamber shown in the lab is actually a thermal/vacuum chamber which simulates the vacuum of space and the temperature extremes encountered in orbit (-300 to +300 degrees F). The chamber is still used in testing satellites prior to launch.
Most of the "military base" exteriors and laboratory scenes were filmed at TRW Space & Defense (now Northrop Grumman Space Technology) in Redondo Beach, California.
The bizarre electronic sounds heard as the Venusian creature approaches the space capsule were taken from a recording called "Noise Study" by James Tenney. It first appeared on a 1962 record album called "Music From Mathematics, Played by IBM 7090 Computer and Digital to Sound Transducer." Its use in this episode marks the first time digitally generated sounds were heard in any movie or television show.
A photograph on a table behind the desk in the living room depicts Martin Landau, who previously appeared in The Man Who Was Never Born (1963) and The Bellero Shield (1964).
All told, this episode has four actors who would later be involved with Star Trek: William Shatner (Captain Kirk), Malachi Throne (Commodore Mendez in "The Menagerie"), Lawrence Montaigne (Stonn in "Amok Time" and Decius in "Balance of Terror"), and James Sikking (Captain Stiles in "Star Trek 3: The Search for Spock").