When Kirk is being tortured, the wide shot from behind shows his arms outstretched almost sideways in the manacles, but when the shot changes to the front, his arms are bent at the elbow, and his wrists extend upward out of the frame.
When Kirk touches the wound on the empath's head he uses his index finger, but when he looks at his hand the blood's on his middle finger.
When Captain Kirk approaches the Vians on the planet surface, he is subdued by their weapon. Still attempting to advance, in prone position, his elbow brushes aside a small green leaf plant. The immediate next view of him, from further back, shows his surroundings, and the plant is not there.
When Kirk is transported from the research station to the Vian's lab, he is lying on a very dusty floor in the research station and leaves a body print in the dust. When Kirk stands up in the Vian's lab after being transported his back is clean.
When the landing party first enter the research station, a chair is sitting on top of a blue square. The blue square vanishes after they watch a video on a computer monitor.
After Kirk is abducted by the Vian teleporter, there is a hand print on the dusty floor that reveals how William Shatner got up between shots. However, the hand print is visible before Kirk disappears, and it can be seen that his hand touches that area when he falls down.
As Kirk recovers from the Vian weapon on the planet's surface, he touches a nearby rock formation to steady himself. The boulder-sized rock visibly shifts under the weight of his hand.
The effect of Kirk and McCoy slowly swinging forward and back is clearly simulated by zooming the camera in and out; the reversals in direction are too sudden.
When the Vian fires his weapon at Kirk after the landing crew finds Gem, it's an obvious change to a stunt double that goes flying backwards.
After Kirk has been released from the manacles used to suspend him we see even red sores on his wrists. However, due to body weight, gravity, and angle of the outstretched arms the marks would be thinner and more pronounced distally but faint or almost non-existent proximally.
When Kirk is being tortured it is easy to spot the suspension ropes holding him from the hips, which also account for his unnatural position.
If there are other planets with life forms in the Vian's solar system, why are Lal and Than only testing Gem to determine if her world is the one that is to be saved from the expectant nova? Why isn't there at least one other inhabitant from each of the other planets to be tested? If the Vians simply test Gem and no others, they might just as well automatically save her world, and not have bothered to subject Kirk and the others to the torture experiments.
McCoy and Kirk's evaluation of Gem makes unwarranted inferences: that being an empath, being able to feel what others feel, somehow means having the ability to physically heal others, and that being mute also means being unable to understand speech.
The first time Kirk, Spock and McCoy are hit with the Vian force field, Kirk says he "can't seem to stand up", even though he is standing.