When this episode, the series' last show, was originally aired on January 16, 1965, a live announcer spoke over the Control Voice's closing statement about returning "next week at this same time." The live announcer stated that The King Family Show (1965) would be seen "next week in this time period." The regular Control Voice closing for "The Probe" was heard only in re-runs.
The microbial alien played by Janos Prohaska evolved into the "Horta" costume he wore in The Devil in the Dark (1967); however, the "Mikie" has rudimentary limbs and reproduces via cellular division.
The amphibious rescue plane at the end is a World War II era Consolidated PBY Catalina.