I recently finished the adaptation of Where No Man Has Gone Before, and noticed a couple of interesting items . . . uhhh, don't know if it is necessary for such an old item, but the following may be considered to contain spoilers - don't want to be scolded.
James Blish notes that Dr. McCoy is on "a special study leave". Granted, the story was written after the fact, but I thought it was an interesting inclusion.
Also noted, at the end Kirk says, "engage" when directing the Enterprise to leave orbit and move on to the next assignment/destination. I always thought that word was a TNG/Picard thing. See, live, err read, and learn.