This Side of Paradise - S1-E25
Continuity mistake: When Kirk and Spock successfully activate a subsonic transmitter, it cuts to a closeup of a spade's metal blade breaking the soil ground, but in the next wide shot Sulu and DeSalle are using two spades made entirely of wood. (00:44:45)
This Side of Paradise - S1-E25
Continuity mistake: As Kirk sits on the deserted bridge, there is nothing out of the ordinary with him. After he sits at the helm position, the camera looks at him over the console, and there's suddenly a spore spewing plant to shoot him.
Suggested correction: The plant did not suddenly appear, it was there from earlier in the episode.
This Side of Paradise - S1-E25
Continuity mistake: As Spock and Kirk are fighting, Spock pushes Kirk to the wall after bending the bar with his first blow. The bent bar falls to the ground and ends up against the wall by Kirk’s feet. Moments later, the bar is nowhere to be found.
This Side of Paradise - S1-E25
Continuity mistake: Kirk threw a "spore flower" across the bridge and it landed towards the front of the bridge. Later on, Kirk returns to the bridge and despite all the crew being on the planet the flower is gone. (00:28:20)
This Side of Paradise - S1-E25
Continuity mistake: As Spock beams up from the planet, Kirk, who is manning the transporter controls suddenly pulls a steel pipe from nowhere. (00:33:55)