TonyPH

Continuity mistake: Valeris seems to appear out of nowhere during the thwarted assassination attempt on Khitomer. The Enterprise crew beam down without her, spring into action, and when Admiral Cartwright yells "Arrest those men!" Spock emerges from the crowd with Valeris in his custody as if she were always there with him or he'd pulled her out of a hat.

TonyPH

Character mistake: Chekov pulls a gun on the Klingon ambassador even though he hasn't been implicated in the conspiracy.

TonyPH

Deliberate mistake: It's not particularly believable that the away team to stop the assassination would consist of the ship's entire senior staff, and raises the question of who was left in charge of the bridge (the answer: apparently nobody, as they return to a completely deserted bridge). Of course this is dramatic license, and at this point the audience won't care or likely even notice.

TonyPH

Question: I always feel like I'm missing something with the scene where Kirk orders the Enterprise to reverse at the beginning of the battle. It confuses the Klingons and leads to a short respite in taking fire, which I would assume was exactly Kirk's intention, but then Kirk himself expresses confusion that the Klingons had stopped firing. What else could Kirk have been trying to do with that action?

TonyPH

Character mistake: There's no apparent reason for Spock's conviction that the gravity boots are a damning piece of evidence that will reveal the assassins, especially considering how useless they prove to be after being found planted in an innocent man's locker.

TonyPH