Re: Some sort of Star Trek - The Original Series [spoilers]
26 - Errand of Mercy
...I get the impression the writer of this episode isn't as capable of writing smart Kirk as some of the others involved in the show.
Interestingly enough this episode was written by Gene L. Coon, co-producer of the series with Roddenberry (some call him The Forgotten Gene). He also wrote Space Seed and several other episodes, and supposedly was the one who originated the concept of The Prime Directive.
He and Roddenberry disagreed often, and Coon left the series halfway through Season Two.
28 - City on the Edge of Forever
Kirk and Spock must travel back in time to undo damage to the timeline caused by a McCoy driven mad by a drug overdose.
This is generally considered the very best episode of original Trek, it's also notorious because the original script was written by Harlan Ellison, and he's still pissed off to this day about how it was rewritten, and the various untruths he believes Roddenberry and Shatner and others have been saying about it ever since.
For his take on the whole saga, check out his book City on the Edge of Forever
I'm seeing another episode called Operation Annhilate! on the wiki, but didn't find this one in my download folder. I might have to track it down.
Not a great episode, suffers from End of the Season There's No Money So Just Get It Done-itis. Sorta interesting because it (briefly) introduces Kirk's brother - one of the few times his family ever gets a mention at all - but not very good otherwise.
There are a lot of good episodes in the second season, when the show mostly hit its stride. There are also some clunkers as well. But the third season, Roddenberry kinda stepped aside, the budgets got cut, and the scripts got pretty goofy overall. The notoriously bad "Spock's Brain" is a third season episode.