- Fanfic Fuel: The Guardian of Forever has appeared in dozens of Star Trek novels.
- Ho Yay: Mixed with a little more Fanfic Fuel - who wants to see Kirk and Spock's domestic AU? Well, here's a glimpse!
- My Real Daddy: To most people familiar with the episode's full development history, Harlan Ellison's original teleplay is a extremely good story that doesn't quite feel like a Star Trek episode, and D.C. Fontana's rewrite of Ellison's story is an absolute masterpiece. Unfortunately, studio politics relating to stopping Ellison from pulling an Alan Smithee, which Roddenberry feared would mislead viewers into thinking it would suck and discourage other sci-fi writers from contributing, resulted in Fontana being uncredited for her part in writing the episode.
- Retroactive Recognition: A very young Joan Collins as the poor but kindhearted Edith.
- Sacred Cow: This is often regarded as the greatest episode of The Original Series, if not the entire Star Trek franchise.
- Tear Jerker: You know it has to happen. You know it's going to happen. It doesn't make it any easier when Edith meets her fate.
- They Wasted a Perfectly Good Character: The Guardian of Forever had so much story potential, but we only see it again twice in canon; of those two, one of those is in the Animated Series, and the other is a two-parter where, paranoid about being misused by malevolent entitled fanatics due to the Temporal Wars, it hides its true nature until near the end.
YMMV / Star Trek S1 E28 "The City on the Edge of Forever"