On the Star Trek thing, Khan's gang were a group of Supermen created from the Eugenics wars in the 1990s, besides a starship seems to be very easy to take over. Anyone with the know how, only needs to take over engineering, lock the doors, and you can take control of bridge functions from there, which is what Khan did. Kirk gave Khan access to documents and all that as a sign of good will, and the fact that people that have been lost since the 1990s would have to find a way to find a niche in a galactic federation. Not only did Kirk give Khan the manuals to the ship, but historical texts as well.
Lt. McGivers was aroused by Khan due to his origin with the fact that much history of the Eugenics Wars and World War 3 have been lost as a consequence of the wars, she initially wanted to learn all she can, but Khan used this as an advantage to seduce her and have her work for him as a mole. She wasn't an idiot, just hormones.
I could understand giving him a history textbook, but giving him the ships manual when you know nothing about his character was just dumb. I could understand giving it to him after you did a BG check and got to know him to see he was not hostile. If he did not read the manual, he would not of had the know how to take over the ship.
With McGivers, They could have written that better, she spent most of the episode kinda dazed and confused, even before Khan seduces her, I can understand a bit of why she why she was this way, just file that under "Dated"
also Khan's makeover of her hair looked like a cross between a mullet and a Beatles haircut.

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I'm probably going to watch episodes in order soon, The reason I saw this one was I saw the beginning of ST2: WOK with my mom, up to the part with the worms and ears, and we decided to see the episode he came from.