^Actually the first episode produced in season 2 was "Catspaw." "Amok Time" was shot fifth, but was aired first because the network wanted to lead off with a Spock-centric episode.
In production order, the episodes Takei missed were #9 of the season ("The Apple"), #13-21 inclusive ("The Trouble With Tribbles," "Bread and Circuses," "Journey to Babel," "A Private Little War," "The Gamesters of Triskelion," "Obsession," "The Immunity Syndrome," "A Piece of the Action," "By Any Other Name"), and #23 ("Patterns of Force"). So I think it's likely that it was that block of nine consecutive episodes that he missed due to The Green Berets, and the other two were just episodes where he wasn't needed.
Thank You, so much, I was confessed what George was saying on interviews about Walter on Season 1 DVD's.
With STAR TREK INTO DARKNESS less than a week away
, I'm not sure that I will finish with TOS before May 17.