Why doesn’t Kirk notice Spock has left the bridge?
Leonard Nimoy beautifully plays the moment Spock, realizing what must be done to restore the Enterprise’s warp engines, resolves to make the ultimate sacrifice to save his shipmates. (It comes about five minutes into the clip from Star Trek II embedded above.)
He turns his head, stares into the distance for a moment—calculating the odds of success, perhaps, or contemplating the fate he’s choosing, or perhaps both—and then leaves his science station for what he (and we) think will be the final time
It’s a powerful moment, especially with every rewatch. But it does strain credulity—also more with every rewatch. I suppose we can forgive David Marcus for not thinking much about Spock leaving his post at such a critical moment. I suspect my reaction might have been along the lines of, “Wait, Captain Spock—where are you going?” But maybe David is simply too preoccupied with the Genesis Device’s imminent explosion (especially since, as we will learn in Star Trek III: The Search for Spock, he took dangerous shortcuts with the Genesis formula).
But can we credibly believe that, during the four-minute buildup to the Genesis Device’s detonation, Kirk never once thought to look back or call out to Spock? This behavior just doesn’t track with their long relationship.
For the Great Bird’s sake, it doesn’t even track with Kirk’s behavior in the previous film! Remember the scene in Star Trek: The Motion Picture when Spock is about to transmit a high-speed, high-frequency friendship message to V’Ger as one of its glowing green energy bolts is headed toward the ship? Kirk turns around to look at and talk to Spock three times in the space of a few seconds! “Mister Spock, transmit now!”
Granted, that ST:TMP moment hinged directly on Spock’s actions. There is nothing Spock can do from his station to help the Enterprise get far enough away from the Reliant to escape destruction. But haven’t we seen Kirk reach out to Spock in so many desperate moments before to think he would do so again—if only to say good-bye?
The shot of Spock’s empty chair after McCoy calls Kirk on the bridge is a gut-wrencher, no question. But it may come at the expense of wrenching plausible behavior a bit too far out of shape.