The background noises heard aboard the ship in the final scene were later reused in Star Trek (1966).
In an interview years later, Fritz Weaver described his experience on the show as "a baptism by fire". The actor was unfamiliar with acting in front of cameras, having spent his career in the theatre. During filming, the director had to guide Weaver along with the use of props and appearing more naturalistic in his performance.
The model of the spaceship in the launch area, and in flight, was taken from Forbidden Planet (1956). The larger "practical" model of the saucer, used for actors entering and exiting, also was used in: On Thursday We Leave for Home (1963), People Are Alike All Over (1960), and To Serve Man (1962).
The dial on Sturka's Ericofon was missing the numeral "9". This wasn't a prop error. Some models of the Ericofon "Cobra" had the cord entry where the 9 would have been.
The painting from The Midnight Sun (1961) can be seen hanging on the wall behind the table during the card game.