The first inkling I had that something was up with Geillis was when she said "barbecue," but it turns out that the word has been in parlance since the 1500s. But "1968" has not, and opened the door to one of the big revelations in the story: Geillis is herself someone who traveled through time, more than 200 years back to Scotland. She would make a great continuing character in the series, and my one regret in this episode would be if she was really burned at the end. True, she murdered her husband - but she's pregnant, and too good a potential ally of Claire's to kill. (I should mention, again, that I haven't read any of the novels, because I want to enjoy the television series on its own terms.)
In any case, Geillis's revelation raises the possibility that there may be other time travelers afoot in this crucial time in Scottish history. And this in turn raises further, intriguing questions: Do the stones always bring people back from the future to this very time in the past? Are the only time travelers women?
The vaccination as a telling "Devil's Mark" was one of the best details of this sort we've seen in the series. (But why does Claire call it a "vaccine" rather than a "vaccination" when she's explaining it all to Jamie?) I love pivotal little details like this in time travel stories - any time traveler from the age of vaccination could be identified as a time traveler by those in the past who were also time travelers, or who, like Jamie, knew that time travel was possible and real. (Hmm ... maybe that's what's motivating some of the anti-vaxxers in our own time ... but I shouldn't be joking about that.)
Fine food for thought. But the emotional payoff in this episode happens in the last few minutes. After Claire tells Jamie "the whole story," he privately decides to bring her back to the Stones and her avenue to her life in the future. He spends a tender evening with Claire, leads her to the Stones, and leaves her. She has every reason to want to get back to Frank and the 20th century, having just come this close to being burned as a witch in the 1700s, but Claire decides that her home - at least, for now - is with Jamie, in Lallybroch.
Outlander continues as time travel on television with heart, savvy, and soul, and it's getting more of that with each episode.
See also Outlander 1.1-3: The Hope of Time Travel ... Outlander 1.6: Outstanding ... Outlander 1.7: Tender Intertemporal Polygamy ...Outlander 1.8: The Other Side ... Outlander 1.9: Spanking Good ... Outlander 1.10: A Glimmer of Paradox
Sierra Waters series, #1, time travel