Margaret's monologue really has an air of finality about it. Maybe that's a product of her own imminent mortality (and it works beautifully from that perspective), but it seems to refer to the mythology/world of TP overall. Interesting that S3 seems to end on an open-ended note, after this monologue sets us up for hard closure. The line about "That which is and is not" does seem to hint at alternate universes/timelines. Also, Margaret talks about the electricity that runs the universe going out, leaving only darkness. Is this what we see in the final seconds of Part 18? Does Carrie/Laura's scream/realization break the universe? Season 4: "What will be in the darkness that remains?"
Kyle has confirmed that Peter Sellers's performance in 'Being There' was a big influence on Dougie, and it shows in this Part in particular. His expression during Janey-E's seduction attempt is pure Chance the Gardener. Although the outcome (he actually enjoys the sex) is an inversion of the classic movie scene. BTW, for those who don't know, original series director Caleb Deschanel was DP on this fantastic little film.
Dougie's chocolate cake obsession (as opposed to the more expected cherry pie) is an odd little quirk. It reminds me of the stories that DKL would eat the same thing for lunch every day for months or even years, then switch to something else. Or maybe it's meant to be a reminder of how hard-up the Joneses are (they're not wasting a slice of that birthday cake!).
It looks like Sylvia is drinking the same shake/smoothie as Nadine. (It's on the table in front of Johnny.)
For those wondering what types of "unscripted" scripted scenes Lynch added sua sponte, a lot of the Candie material strikes me as Exhibit A.
Gordon says he sensed "it" when Diane hugged him. We now know that he sensed not that she was a traitor, but that she was a tulpa. I actually picked up on Gordon being awkward during the hug way back in Part 4 (and wondered if it had something to do with a healthy paranoia about sexual harassment suits, given what Denise says about his reputation). Lynch did some great acting work this season, and it's impressive that I picked up on his physicality in that scene right away.
I love the dark subtle joke that Richard's plan to gas Miriam failed because he kicked in the door pane earlier. Not the brightest bulb, that Richard.
While I mostly love S3, I've sympathized with the Profoundly Disappointed throughout the show's run. I'm delighted to have an answer to the question "What does a David Lynch sequel look like?" (answer: it's even more elliptical than I could possibly have imagined), but I think those who are frustrated/disenchanted by this thing are well within their critical rights. For instance: who in their right mind went into this season thinking, "What I really need from a third season of TP is a Vegas casino insurance claim war"? And yet...on some level, that plotline is similar to the Ghostwood scheming of the first season, and perhaps the closest thing in the new show to the original seasons' soapy roots.