In the first bridge scene, there is a man at the communications station. However, after the Enterprise activates its deflector beam, stock footage of Uhura (who otherwise does not appear in the episode and is not listed in the end credits) is included in the individual reaction shots of the crew.
Miramanee rescues a drowned boy from the bottom of the river. However, as she sits the boy down, his clothing is still dry and, after Kirk administers artificial respiration, the boy does not cough up any water. Had his clothes dried by sunlight, too much time would have elapsed for the boy to be revivable.
When the attempt to deflect the asteroid fails, Spock makes a last-ditch effort to break it up with a sequence of phasers. Sulu announces, "Phaser 1 firing," "Phaser 2 firing' etc., but the special effects visuals (in both the original release and the re-mastered version) only show the usual twin main phasers repeatedly firing from their usual locations. Spock -- with disastrous results -- then orders, "Rig for simultaneous firing... Commence simultaneous bombardment", and we see an identical shot before the ship's engines are wrecked.
Spock orders the Enterprise to rush towards the asteroid at Warp Nine, at which it has been speeding for several hours. This seems to imply the asteroid would be far outside the planetary system, possibly light years away. This would mean the asteroid would require thousands of years to reach the planet.
When blasting the asteroid, the pairs of phaser beams leave the Enterprise in a divergent pattern but each time the shot changes to the asteroid, the beams converge at the same point. As the beams travel linearly, this is geometrically impossible unless at least one of them was somehow reflected on the way.
Spock gives the coordinates of the settlement as "bearing 117 mark 4" with respect to the obelisk. The "mark 4" specifies a plane perpendicular to the "bearing 117". This would place the settlement uphill, which is unlikely since it is near water. Moreover, 3-D coordinates aren't necessary on a planet (unless something is located in the air!).
In the opening scene, Spock describes the approaching asteroid as "...nearly the size of Earth's moon...". However, scenes showing the Enterprise near the asteroid clearly show that the body could not have been more than a few kilometers in diameter (compared to the 725-meter long Enterprise). The approaching body has far more curvature than a Luna-sized one would have. However, since we don't know how far away from the asteroid the Enterprise was, it cannot be calculated how big the asteroid actually was.
When Captain Kirk has to be abandoned on the planet, there is no attempt to leave a search party (comprising the usual red-shirts-of-the-week) to look for Kirk while the ship is away. However, it would be counter to the Prime Directive, to leave a landing party on the planet for an extended time, as an unintended contact might occur.
When debating on whether to return to the ship or search for Kirk, McCoy exclaims that the asteroid won't reach the planet for two months; however, later in the same conversation, Spock uses two rocks to show the position of the planet and the changing position of the asteroid. If the speed of Spock's "example" is correct, the asteroid will hit the planet in mere minutes, not months. But there is no real attempt by Spock to show the distance involved to scale, except illustrate the movement of the asteroid toward the planet.
Miramanee makes the statement "the Earth will tremble and the sky will darken" but, being light years from Earth, it is unlikely anyone there would know the name. Others correctly stated "the ground will tremble".
However, she presumably meant "the earth" (i.e., the ground). (The words were spoken, not written, so there is no way to distinguish.)
Kirk knows he's not a god even with his amnesia. Yet he never corrects anyone that claims he is. Kirk himself neither believes in gods nor of the servitude to them. This was proven Who Mourns for Adonais? (1967) when he dismissed Apollo as a god, and The Apple (1967) when he believed the planet's inhabitants were servants of the serpent head Vaal. (Among other examples.) In this instance, though, he is not himself; however, "playing along" with his current circumstances is a tactic he has often used - e.g., pretending to be Dr. Roykirk in The Changeling (1967) - and he might be using it instinctively here.
In the beginning, Kirk, Spock, and McCoy are beamed down to the planet and materialize on a recently graded dirt road, obviously done to hide tire tracks. The primitive inhabitants don't have cars or the necessary equipment to produce and maintain the road.
Nurse Chapel beams down from the Enterprise (with presumably calm air) into a wind storm; however, the image makes it look like a similar storm is occurring in the Enterprise transporter room. Similarly, when Spock beams down, his hair is shown blowing in the wind even before he fully materializes.
The lower part of the sideburns on Kirk are obviously fake.
When Captain Kirk summons the Enterprise, he says "Kirk to Enterprise", for which he immediately drops down into the Obelisk..
Yet, when Captain Kirk tries to reenter the Obelisk, he says "Kirk to Enterprise" for which Scotty says "Ay, Captain". It is only then the Obelisk opens.
One can only assume it was Scotty's answer opened the door at the end, but previously it was Captain Kirk calling the Enterprise that opened...
Yet, when Captain Kirk tries to reenter the Obelisk, he says "Kirk to Enterprise" for which Scotty says "Ay, Captain". It is only then the Obelisk opens.
One can only assume it was Scotty's answer opened the door at the end, but previously it was Captain Kirk calling the Enterprise that opened...
It is clear when they are outside the temple. That is only "windy" there. The trees in the background are not blowing. There are no waves on the lake at all. With wind that strong there would be big waves on the lake.
When the medicine badge is removed from Salish's head, it stretches, obviously made of elastic. Miramanee is later puzzled by Kirk's elasticated top which has no straps.
When Salish confronts Kirok on his wedding day, he says Kirok's name without moving his lips.
Given the urgency of heading off the asteroid, what was the landing party doing on the planet surface at the beginning? This seems an unnecessary waste of precious time. Their ability to confirm the presence of human life from orbit, via ship's sensors, had long since been established.
At the beginning, Kirk asks about the odds of finding another Earth-like planet. Spock indicates the odds are astronomical. This makes no sense, as there have been at least three prior missions where they have encountered Earth-like planets: Miri (1966), The Omega Glory (1968), and Bread and Circuses (1968). Others missions were to planets that showed Earth-like development, but those were caused by external influences from Federation visitors.
With the Enterprise's warp drive crippled and taking almost 2 months to return to the planet, there's no explanation as to why they don't simply call Star Fleet Command to request rescue. Indeed, Scotty says that the ship can't be repaired except at a repair base, so they will have to call for rescue by the end of the mission anyway.
With the Enterprise only using phasers in at attempt to destroy the asteroid, no mention is made about using photon torpedoes or better yet, having additional starships arrive to destroy it altogether.
With the planet and the inhabitants not being Federation members, there is no plausible reason, other than simple decency, for Starfleet's interference in trying to deflect the asteroid.
At the beginning, Kirk, Spock, and McCoy are standing at the edge of the forest by the riverside without any camouflage or concealment, where the Indians could easily look over and see them. Usually, these characters go to great lengths to make themselves invisible when on an observation mission like this, in accordance with Starfleet's Prime Directive of not doing anything to interfere with or unduly influence a less-advanced culture.
Spock refers to the characters on the obelisk as "incised symbols." They are raised, which is the opposite of incised.
The Native Americans depicted display none of the cultural elements of the tribes described by Kirk & Co. (Navajo, Delaware, Mohican) The houses are tipis, used by plains peoples. The clothing bears no resemblance to actual Native American clothes, and the names of the characters match no Native naming styles. Also, the Navajo were not peaceful, but were very fierce warriors. The Mohican are a fictitious tribe created for the stories of James Fenimore Cooper who combined the names Mohawk and Mohegan, also warrior tribes. The Delaware were not called "Delaware," but rather, were the Lenne Lenape, as a scholar should refer to them in formal references.