The episode is widely disliked, so you probably haven’t seen it in a while. I encourage you to watch it again. It’s not hippies and bouncy songs. It’s a mass murderer and his enthralled gang.
You have likely never seen this licensed Star Trek kids’ booklet. It was made in Canada and the only one I have ever seen in person is the one I own. But you can download a copy right here.
The Inside Star Trek newsletter is an invaluable source for Star Trek’s early voices. Issue 1 detailed William Shatner’s busy schedule, told us about searching through studio garbage and shared a made-up story about the Vulcan IDIC medallion.
George Takei was thrilled when John Wayne cast him in The Green Berets, but that robbed Takei of the chance to pick up a Tribble with Uhura on K-7.
Except that story is not quite true.