How did that Tribble die anyway? I thought McCoy was more ethical than to experiment on small fuzzy animals. ;)

They didn't even use the classic Tribble sounds.

One other Khan nitpick is in Space Seed, Kirk, McCoy, and Scotty know something of Khan's history once he's been positively identified. They even express some admiration for Khan (to Spock's surprise) as he was somewhat benevolent compared to his contemporaries. "The best of the tyrants."

It might have been better had they tossed off a line about Harrison having had extensive facial surgery.