This Side of Paradise - S1-E25
Plot hole: When Captain Kirk is the last person unaffected by the spores, he's on the bridge lamenting the fact that he is trapped in orbit above the planet since he can't pilot the ship alone. He also can't call for help because Lt. Uhura sabotaged long range communications. but Captain Kirk has somehow forgotten about the shuttle craft. He could have easily escaped on one of those.
Tomorrow is Yesterday - S1-E20
Factual error: Towards the end of the show the Enterprise is leaving Earth orbit and heading towards the sun. We see the Earth diminish and the moon appear looking exactly as it does from Earth. From this angle we should be seeing the "dark side" of the moon, which looks completely different. (00:40:50)
Trivia: Gene Roddenberry created the transporter as an easier (and cheaper) way of getting Enterprise crew members onto a planet's surface, rather than landing the ship on the planet.
Question: When Kirk and crew neutralized all the androids on the planet, what happened to the androids on the Enterprise running the ship?
Answer: If all the humans beamed down and only Androids were on the ship as Larry Mudd said then how did they get back aboard the Enterprise if all the robots were shut down.
Harry Mudd. The androids were reprogrammed on the planet, and the crew was beamed aboard. The ship was on autopilot.
Answer: After causing Norman to overload, all of the other androids shut down. The same could be said for the androids on the Enterprise.