What happened to Spock's superior Vulcan hearing? He was only a few feet away when McCoy first enters the mission and talks to Edith.
Why does Spock "borrow" the fine tools by picking the lock instead of just asking permission? Edith Keeler already knew that he was working on a
"radio" on his off-hours, was there some reason he thought she wouldn't let him use them?
Spock clearly determines earlier that Edith dies in a street accident. However, when Kirk saves Edith from a fall inside a house, Spock says that might have been the accident he foresaw.
Even with the various unpredictable factors Spock mentions earlier, there doesn't seem to be any way he could confuse a street accident for a house accident.
Although Spock and Kirk are both present when the Guardian says it will show them "their" history, it only shows Earth's history.
In the scene a deranged McCoy confronts the homeless man just after arriving in 1930, DeForest Kelley is wearing a ring on his left pinky. It wasn't there before and afterward.
episode contains the only line of dialogue in the classic series
where someone swears when Captain Kirk says "Let's get the hell out
McCoy is knocked out on the planet, then wakes up a few minutes later and makes it into the Guardian...with a phaser. Assuming the
landing party intelligently decided to disarm him after they captured him, where'd he grab the phaser?