"If I were human, I believe my response would be 'Go to hell '." (beat) "If I were human."
"Second star to the right ...and straight on till morning."
The cast's signatures appearing at the start of the credits. A beautiful gift to the fans from the original crew's final outing.
Sulu blatantly disregarding Starfleet orders to help Kirk and the others on the Enterprise. He may now be The Captain of the other ship, but he's still part of the crew.
The Star Trek: Voyager episode "Flashback" adds a little extra heartwarming for good measure.
Sulu: You'll find that more happens on the bridge of a starship than just carrying out orders and observing regulations. There is a sense of loyalty to the men and women you serve with; a sense of family. Those two men on trial... I served with them for a long time. I owe them my life a dozen times over. And right now they're in trouble, and I'm going to help them; let the regulations be damned.
Tuvok: Sir, that is a most illogical line of reasoning.
Sulu: You better believe it. Helm, engage!
Worf's grandfather showing that honor runs in the family by valiantly doing his duty as the defense councilor during Kirk and McCoy's Kangaroo Court trial.
Kirk summing up his relationship with Spock:
Kirk: You're a great one for logic. I'm a great one for rushing in where angels fear to tread. We're both extremists. Reality's somewhere in between.
Kirk and Klingon Chancellor Azetbur at the Khitomer Conference. "You've restored my father's faith." "And you've restored my son's."
In the climactic battle, Spock turns to McCoy and asks if he'd like to help him "perform surgery on a torpedo". McCoy's response?
At the end, when the Excelsior leaves, McCoy comments "My God, that's a big ship." Scotty responds, "Not so big as her captain I think", showing how they still consider Sulu part of the Enterprise "family". It's also nice to hear Scotty showing respect to the Excelsior given how dismissive he was of it in Star Trek III and IV.
McCoy: And the good news is they're not going to prosecute.
Uhura: They might as well have prosecuted me. I felt like Lt. Valeris.
McCoy: Well, they don't prosecute people for having feelings.
Chekov: Just as well, or we'll all have to turn ourselves in.
Even as he laid dying from a renegade Starfleet attack, Gorkon still implored Kirk to continue the peace process, saying "Don't let it end this way, Captain..." with his last breath. Later, Kirk told McCoy "Gorkon had to die before I realized how prejudiced I was" and regretted not taking him at his word from the get-go.