What bothered me the most was Kirk defending Spock in "Balance of Terror" from Stile's racism...and then, many episodes later, he and McCoy refer to Spock as a "devil" in "The Apple." WTF??? Yeah, I know McCoy and Kirk were just kidding, but they said that to Spock's face.
Not very cool or professional to do that to someone that you considerto be your best friend--especially if he's an officer who just got hit by a lightning bolt. If I were Spock, I'd have Vulcanized both their asses on the spot. lol