1. Where No Man Has Gone Before (Episode 2), The Menagerie (Episode 11)
The Plot(s): Captain Kirk's best friend gets god-like powers. I already told you the plot for The Menagerie.
The Screw Up: SPOCK SMILES! In Where No Man Has Gone Before, Mr. Spock and the Captain are playing chess. Kirk remarks that Spock plays "a very irritating game of chess." To which, in a clunky bit of exposition, Spock responds, "Irritating? Ah, yes, one of your Earth emotions." While he says the second sentence, he smiles smugly, which undercuts his statement completely. In The Menagerie, on an away mission with his old crew, he sees some delightful plant life, and beams a smile. Maybe Pike was able to make him feel happy. Maybe that's why he did all that illogical s**t in The Menagerie.
Cool Trivia: Spock smirks slightly in
Mudd's Women, but I thought that could be explained away by the powerful "allure" the women give off.) *For more in-depth nitpicks, I urge all of you to read
Phil Farrand's The Nitpicker's Guide for Classic Trekkers. It is a must for anyone who calls themselves a Trekkie.