Something I've been pondering about this episode is WHEN did the illusion begin for Kirk and crew? My only speculation is it began the moment the Melkotian buoy spoke to the crew, "Aliens!" in the respective languages. And, of course, it ended when Kirk spared Wyatt Earp, finding himself and the others back on the Enterprise, with the Melkotian buoy about to explode. If that's the case, it's a very powerful telepathic illusion, as opposed to the classic trope of dream sequences, starting when a character closes one's eyes, and it seems only a split blink occurred, but that's when the dream begins, and then ends when the character finds themselves back where they were, or that some time had passed, but still a dream...