Zar holds his hand up to a light in the Seaview's corridor and comments that humans haven't learned to generate light without heat. What was almost certainly a bit of "throwaway" dialogue anticipated the widespread use of LED lighting (in the very early and costly stages of commercial development in 1962) by several decades.
This episode takes place in the 1970s.
Commander Lee starts to reach for a military .45 automatic in the holster of a crewman. The hammer is round which is a Commander type hammer not a full size military hammer. Colt Commanders were not issued to troops.