I imagine the conversation in the Fringe writers' room went something like this when cooking up the latest episode, "Lysergic Acid Diethylamide":
Head Writer: Okay guys, we stuck William Bell in Olivia, now we need to figure out how to get him out.
Silence, as writers pretend to take notes and avoid eye contact. Finally, a hand is raised.
Head Writer: Yes you, with the dreadlocks and the 1972 Grateful Dead concert t-shirt that smells like 15-day-old baloney.
Hippie dude: Why don't they all, like, drop a blotter and go into Olivia's mind, man?
"LSD" was a "special" episode of Fringe written by showrunners Jeff Pinkner and J.H. Wyman (with a little help from Akiva Goldsman), and it was more of an homage to the show's cousins in the entertainment industry than a necessary step in the show's mythology. But was it a fun trip? Awww yeah.
Borrowing ideas from The Matrix, Inception, A Scanner Darkly, and heck, even Song of the South, "LSD" saw Peter, Walter, and Bellivia being dosed with acid so they could share consciousness and dive into Olivia's mind to put Bell's consciousness into a computer and pull Olivia's to the front. Or something like that. I opted just to roll with it, and it worked.
It even worked halfway through the episode, when everything turned into a living comic book—even though Peter didn't look like Peter and zombies roamed on rooftops. We've seen other shows try animated sequences with less success, and Fringe's attempt fared better than most.
Fringe has changed substantially since its first season, drifting much further away from "fringe science" and more toward pure, theoretical science-fiction where there are almost no boundaries. It's a healthy step for this show, which now relies on characters over technology, scientific experiments, and the slimy parasites that sold the show in the first place. It's also why "LSD" works now, most of the way through Season 3, and why "Brown Betty," the show's musical episode from Season 2, did not. The Fringe universe—not its on-screen canon, but the universe of the series—has expanded enough to allow a risky move like "LSD," and it's fair to assume this won't be the last "special" episode.
Though the goal of "LSD" was to get our Olivia back (and totally blow your mind), the episode ended with a head-scratcher that proves it was more than just a side trip into the bizarre. Olivia's mind manifested a mystery man with an "X" on his shirt—someone who Olivia coolly announced would kill her. Granted, most people who trip something is going to kill them, but I think this one is for real. Who is this man, and how literal was her comment about him killing her? Could it be the man who will kill Fauxlivia? And why did Olivia identify him so matter-of-factly? Like I said, head-scratcher.
The whole experience seems to have changed Olivia, possibly for the better. She's strong again, leaving her debilitating fear behind her not only in Toon Town, but also in real life. This means that ultimately, Olivia could end up with Fauxlivia's strength, thus fortifying her love with Peter and guaranteeing that the Doomsday device will blow up the other universe. LSD: Is there anything it can't do?
And finally, have we seen the last of William Bell? His consciousness was lost like a term paper to a disc-read error, but do you think he's gone forever? Has he slipped into the internet to live a life of spying on people's email and communicating via Chat Roulette? Is he the Ghost in the Machine?
I'm sure some fans will write off "LSD" as a failed attempt at something more, but I don't think it was meant to be anything more than a fun, experimental diversion from what has otherwise been a brilliant, heavy season. Mission accomplished.
... How great was Lance Reddick (Broyles) in this episode as the comic relief? It's nice to see Reddick get an opportunity to do more than just walk around with his chest puffed out, barking orders.
... When will Astrid get invited to the party? I want to see her frolicking in the strawberry fields!
... Have you read my favorite book, "The Doors of Perception," by Aldous Huxley?