To add a direct quote from William Shatner's Star Trek Memories...:
Unfortunately, what Gene meant by "Let's shoot it two ways" was that we'd shoot the Kirk/Uhura kiss twice. In the first take, we's actually kiss on camera, and in the second, Nichelle and I would turn our bodies as we embraced, so that my back was to the camera long before our lips would have ever touched. We'd give the impression of kissing without ever touching lips. Sadly, when push came to shove, the network got their way and the no-contact kiss made it to the airwaves. For that reason, the widely held assumption that Star Trek features the first interracial kiss in the history of television is absolutely untrue. And if you happen across the episode, look closely and you'll see what I mean.
And from Nichelle Nichols's Beyond Uhura...:
Finally, we were back on the set, ready to shoot the scene Shen suddenly the director realized that this would be an interracial kiss. He panicked... skipping a bit ...Knowing that Gene was determined to sir the real kiss, Bill [William Shatner] shook me send hissed menacingly in his best ham-fisted Kirkian staccato delivery, "I! WON'T! KISS! YOU! I! WON'T! KISS! YOU!"
It was absolutely awful, and we were hysterical and ecstatic. The director was beside himself, and still determined to get the kissless shot. So we did it again, and it seemed to be fine. "Cut! Print! That's a wrap!"
The next day they screened the dailies, and although I rarely attended them, I couldn't miss thus one.Everyone watched quietly as Kirk and Uhura kissed and kissed and kissed. And I'd like to set the record straight: Although Kirk and Uhura fought it, they did kiss in every single scene. When the non-kissing scene came up, everyone in the room cracked up. The last shot, which looked okay on the set, actually had Bill wildly crossing his eyes. It was so corny sync just plain bad it was unusable. The only alternative was to cut out the scene altogether, but that was impossible without ruining the entire episode. Finally, the guys in charge relented. "To h--- with it. Let's go with kiss." I guess they figured we were going to be canceled in a few months anyway. And so the kiss stayed.
My all-time favorite Nichelle quote:
"That is so-o-o-o-o-o find. When I get to know you better I'm going to ask for a ride in this Stingray. It's BAD, you know."