Watch the scene of the Klingon ship in San Francisco Bay. The whales have survived the crash, the probe has left, all’s right with the world. Kirk is in the bay and Gillian is clinging to the side of the Klingon ship. He offers his hand to her as if to shake hands; instead, he pulls her into the water. That’s when Spock laughs.

Chekov and the FBI agent talk past each other. Chekov knows what he’s saying but not what the agent asks him, and of course it never occurs to the G-man that he’s interrogating someone who won’t even be born for another 300 years. To the agent, the only thing that makes sense is that Chekov is mentally deficient.