In this episode, Kirk can barely get Spock to talk about the Pon Farr. It is said to be "a very personal thing to the Vulcan people." However, in "The Cloudminders" in the third season, Spock talks about it casually to a local. In Star Trek III when the young Spock enters Pon Farr, Saavik nonchalantly tells David about Pon Farr without so much as batting an eye. In the ensuing years between the episode and the movie, has the Pon Farr now become common knowledge? Worse, in Star Trek: Enterprise, which precedes this episode by almost a century, they talk about Pon Farr freely as well. This is basically the only episode where they don't talk about it freely.