Revealing mistake: The stuntman playing Latimer is obvious when he falls after being hit in his back with the creature's spear.
Visible crew/equipment: As the camera swings around to simulate the crewman's gaze, the top of the background is visible for a second until the camera pans down.
Continuity mistake: While Kirk questions Spock about his command decision on the Galileo, shots of Uhura and Mears show the ladies close together at Uhura's station with Mears' hands hidden but close up shots of McCoy show Mears and Uhura in the background further apart from each other and Mears' hands in front of her body.
Continuity mistake: As the Galileo re-enters the atmosphere, you can see Scotty in the copilot chair. His hair is parted on the left side, but in the interior shot, it's parted on the right.
Factual error: Trelane has been watching Earth as it was 900 years ago (14th century in the film), but his style is more 17th century, and he mentions Napoleon who lived in the 19th century.
Factual error: The harpsichord Trelane plays is far too short and has pedals like a piano.
Continuity mistake: When the Enterprise tries to escape Gothos, and the planet blocks the ship's path each time, Gothos is very transparent, where the stars could be seen through the planet.
Revealing mistake: When first seen on Gothos, the "frozen" Kirk's eyes blink.
Other mistake: It's been established the planet is extremely dangerous to human life but when Jaeger, McCoy and DeSalle beam down they just have a simple mouth/nose mask on.
Revealing mistake: As Kirk turns to run on the castle steps, an iron bar barricade appears, blocking his path. When it does, watch the castle wall, and the barricade. It seems to slide just a few inches to line up correctly in the shot, showing poor editing.
Continuity mistake: After swiping at Trelane to score a hit, which Trelane avoids easily, Kirk throws the sword away, which hits a bush as it falls. When Trelane calls up another sword, the bush suddenly stops moving.
Revealing mistake: As Trelane takes a swipe at Kirk, he hits a tree branch. As it breaks away, the building material it was made from is revealed, rather than it being wood.
Revealing mistake: In Trelane's castle, Kirk and Sulu are supposed to be frozen, but they slightly waver.
Continuity mistake: After DeSalle tries, and fails, to call the ship, he shakes his communicator, and the grille closes, but is opened again in the wide shot.
Revealing mistake: Just before Kirk finds himself in Trelane's "courtroom", look behind Kirk on the bridge above Spock's work station. The viewscreen with the planet on it is actually a piece of paper that's coming away from the wall.
Continuity mistake: During the attack on the outpost, as Spock arrives in his foxhole, Kirk puts down the box of ammunition and positions the grenade launcher. We cut to a higher angle as Spock scrambles around to the Captain's left, and Kirk is putting the box down and positioning the launcher all over again. As the action was supposedly continuous, there wasn't time for Kirk to pick the items up and set them down a second time. (00:08:40)
Other mistake: Kirk's voice-over log entry says he's been "placed on the surface of an asteroid." The Metrons earlier referred to it as a planet prepared for them with a suitable atmosphere. How and why does Kirk suddenly assume that it's an asteroid rather than a full sized planet? As an experienced space veteran, Kirk, who has already been told that it's a planet, would never make such a mistake. (00:23:45)
Continuity mistake: The giant rock sitting on the promontory, in long shot, is much larger than the Kirk stand-in stunt man who climbs the rock face to reach it. Next shot, when Kirk pushes the boulder over the edge, it's suddenly much smaller than he is. When it lands on the Gorn, the rock is even smaller - now less than half its original size. (00:31:35)
Revealing mistake: At different points during the Metrons' transmission to the Enterprise, both Kirk and the Gorn pop into the picture a few seconds after the rocky landscape appears. (00:37:00 - 00:37:55)
Continuity mistake: After Kirk tells the Metrons that he won't kill the Gorn, he yells out "you'll have to get your entertainment someplace else." Two seconds later, Kirk turns his head to the side and looks stunned. That look of surprise takes place a full second before the Gorn starts to disappear. (00:45:47)
Chosen answer: If they're in orbit, they're being pulled along by the planet's gravity well, therefore, impulse engines would only be used for minor corrections and would be "on standby" while in orbit, but not active. (Like keeping your car idling without revving the engine and creating plumes of exhaust).
Captain Defenestrator
Thank you for the info.
Movie Nut