Shore Leave - S1-E16
Revealing mistake: There is a wooden or straw hut - some kind of man-made structure - visible in the lower-left of the frame behind Kirk and Bones as they walk. (00:12:30)
Shore Leave - S1-E16
Factual error: In a scene where Kirk and McCoy are examining the tracks left by the White Rabbit and Alice, in the background behind some trees can be seen a white building (the shoot was done at Africa, USA, an animal theme park). (00:13:30)
Shore Leave - S1-E16
Character mistake: When Spock beams down after calculating there was just enough energy left for him to do so, Sulu and Kirk watch him materialize, and Sulu says, "Someone beaming down from the bridge." From the bridge? Shouldn't he have said "from the ship"? No one ever beamed down directly from the bridge, but even if they could, how would Sulu know that's where they'd come from? (00:28:00)
Shore Leave - S1-E16
Revealing mistake: Stock footage turns the single plane strafing Rodriguez and Angela into two attacking planes for a moment. It becomes one plane again when it flies over Kirk and company. (00:33:40)
Shore Leave - S1-E16
Revealing mistake: After Rodriguez and Angela run from the strafing plane, they end up stopping next to a tree. Angela falls to the ground without Rodriguez knowing that she was hit by the gunfire. He continues to watch the plane disappear with his head looking upwards. When his head comes back down, rather than looking towards her to talk (where her face would be if she was standing), his eyes immediately look down at her on the ground...as if he'd been expecting that she'd be lying there all along. (00:34:01)
Shore Leave - S1-E16
Visible crew/equipment: While Kirk is with Spock, when Finnegan shows up again Jimmy boy gives in to the chase, then as Finnegan runs and shouts, "Here I am," the shadow of the camera equipment is visible at the bottom right side of the screen, as it follows Finnegan. (00:35:55)
Shore Leave - S1-E16
Continuity mistake: Finnegan flips Kirk over his shoulder near the end of their fight. When Kirk lands, his uniform is still completely intact, but when we cut to a close-up, his shirt is suddenly shredded. (00:38:30)
Shore Leave - S1-E16
Revealing mistake: Near the end of the episode, the heavy chains restraining the "loose" tiger are visible both around his neck and running across the rocks to the right of the shot. (00:42:35)
Shore Leave - S1-E16
Continuity mistake: Don Juan tears Yeoman Barrows' tunic at the right shoulder. Near the end, when she changes from the fairy tale dress back into the tunic, the torn right shoulder is suddenly mended. They're cut off from the ship by the power drain, so she couldn't have beamed up for a new one. She emerges from the bushes after changing, and now her tunic is torn at the left shoulder. (00:43:25)

Shore Leave - S1-E16
Visible crew/equipment: You can see the shadow of a boom mic moving on a tree just as the Caretaker appears. (00:44:05)
Shore Leave - S1-E16
Plot hole: The planet is supposed to be uninhabited but nobody seems surprised that there are walkways everywhere.
Shore Leave - S1-E16
Revealing mistake: When Yeoman Barrow places her tunic on a shrub while changing, automobiles can be seen in the background through the brush.
Shore Leave - S1-E16
Continuity mistake: At the end Angela is not with the group then strangely reappears without any reason given.
Shore Leave - S1-E16
Character mistake: Yeoman Barrows is a crew member on an star ship and I assume has experienced or has trained to experience many different things she will encounter on the tour of duty but she freaks out and cries uncontrollably just because she sees Don Juan.
Shore Leave - S1-E16
Revealing mistake: During the scene with Sulu and the samurai, each actor casts three shadows. Plus as the samurai rushes Sulu, the "sky" appears black behind him.
Continuity mistake: When Kirk informs Galileo that all systems are clear for takeoff, in the shot from inside the shuttlebay as Galileo turns to launch, the shuttlecraft Columbus is also in the hangar deck, but when Galileo exits Enterprise the Columbus is gone in the exterior shot. (00:01:45)
Continuity mistake: In the first scene when Spock is piloting the shuttle craft out of the Enterprise and into space, as the bay doors open you can see both the ship's shuttles, the Galileo, and right behind it the Columbus. Yet as soon as the Galileo clears the bay doors, in the immediate reverse shot, the bay is empty and the Columbus has disappeared. (00:01:45)
Continuity mistake: After Spock tells Boma and Gaetano that he's in command and they should fire only to frighten, not to kill, one of the creatures throws a spear and then his shield at the trio, and when the shield hits the ground it's much smaller than the huge shield lying on the ground in the next close-up. (00:23:15)
Character mistake: In the scene when the shuttle is finally repaired and lifting off the planet, Spock asks "Fuel status?" and Scotty incorrectly answers "15 pounds PSI, sir. Approximately enough for one orbit." The correct answer would be simply "15 PSI" without the redundancy, as the P in PSI already signifies pounds. As an engineer Scotty would know this. (00:42:00)
Visible crew/equipment: After Spock has jettisoned Galileo's fuel and ignited it, when it cuts to the bridge aboard Enterprise the shadow of the camera/equipment can be seen moving across the helm console.






Suggested correction: They're on a planet where their every thought can be almost instantly created in physical form. Within the context of the episode it wouldn't be unusual to see literally anything in the background. Perhaps one of them was thinking about something involving that structure and it was being constructed for them.