The surprise is Bell, last seen and still in residence in Olivia's body, now a cartoon figure in Olivia's mind - or rather, the way that Fringe represents the contents of Olivia's mind is, mostly, through animated figures. Walter and Peter discover this when they enter Olivia's mind in search of Olivia, which is necessary to get Bell to leave so Olivia can take charge of her body once again. And when Walter and Peter find Bell, a cartoon, in Olivia's mind, they turn into virtual cartoon figures, too.
So, at this point, we have Inception (entering someone's mind) and Tron (the move from physical to virtual worlds - a Second Life right before our eyes. How does The Walking Dead come in? In this world of Olivia's mind, first some flesh-and-blood zombies (or maybe they're alive) and then some cartoon zombies who are 100% zombies chase our heroes. Totally unnecessary plotwise, but, hey, I'm a fan of The Walking Dead, and the TV series is after all an adaptation of the comic book series.
On the subject of homages, Bell aka Leonard Nimoy also says "aye, aye, Captain" to Walter, in a sly reprise of Spock to Kirk.
Also worthy of note are the WTC Twin Towers. Why would they be in Olivia's mind? I thought at first that maybe the mind was Fauxlivia's, but an equally good explanation is Olivia recently saw the WTC when she was "over there".
As to plot: Bell apparently takes his final leave, but since he doesn't like goodbyes, anything is possible in the future. In the more immediate up ahead, Olivia thinks someone will kill her ... but how she got knowledge of her own future is anyone's guess...
5-min podcast review of Fringe
See also Fringe 3.1: The Other Olivia ... Fringe 3.2: Bad Olivia and Peter ... Fringe 3.3: Our/Their Olivia on the Other Side ... Fringe 3.5: Back from Hiatus, Back from the Amber ... Fringe 3.7: Two Universes Still Nearing Collision ... Fringe 3.8: Long Voyages Home ... Fringe 3.10: The Return of the Eternal Bald Observers ... Flowers for Fringenon in Fringe 3.11 ... Fringe 3.12: The Wrong Coffee ... Fringe 3.13: Alternate Fringe ... Fringe 3.14: Amber Here ... Fringe 3.15: Young Peter and Olivia ... Fringe 3.16: Walter and Yoko ... Fringe 3.17: Bell, Olivia, Lee, and the Cow ... Fringe 3.18: Clever Walternate
See also reviews of Season 2: Top Notch Return of Fringe Second Season ... Fringe 2.2 and The Mole People ... Fringe 2.3 and the Human Body as Bomb ... Fringe 2.4 Unfolds and Takes Wing ... Fringe 2.5: Peter in Alternate Reality and Wi-Fi for the Mind ... A Different Stripe of Fringe in 2.6 ... The Kid Who Changed Minds in Fringe 2.7 ... Fringe 2.8: The Eternal Bald Observers ... Fringe 2.9: Walter's Journey ... Fringe 2.10: Walter's Brain, Harry Potter, and Flowers for Algernon ... New Fringe on Monday Night: In Alternate Universe? ... Fringe 2.12: Classic Science Fiction Chiante ... Fringe 2.13: "I Can't Let Peter Die Again" ... Fringe 2.14: Walter's Health, Books, and Father ... Fringe 2.15: I'll Take 'Manhatan' ... Fringe 2.16: Peter's Story ... Fringe 2.17: Will Olivia Tell Peter? ... Fringe 2.18: Strangeness on a Train ... Fringe 2.19: Two Plus Infinity ... Fringe the Noir Musical ... Fringe 2.21: Bring on the Alternates ... Fringe 2.22: Tin Soldiers and Nixon Coming ... Fringe Season 2 Finale: The Switch
See also reviews of Season One Fringe Begins ... Fringe 2 and 3: The Anthology Tightrope ... 4: The Eternal Bald Observer ... 7: A Bullet Can Scramble a Dead Brain's Transmission ... 8. Heroic Walter and Apple Through Steel ... 9. Razor-Tipped Butterflies of the Mind ... 10. Shattered Pieces Come Together Through Space and Times ... 11. A Traitor, a Crimimal, and a Lunatic ... 12, 13, 14: Fringe and Teleportation ... 15: Fringe is Back with Feral Child, Pheromones, and Bald Men ... 17. Fringe in New York, with Oliva as Her Suspect ... 18. Heroes and Villains across Fringe ... Stephen King, Arthur C. Clarke, and Star Trek in Penultimate Fringe ... Fringe Alternate Reality Finale: Science Fiction At Its Best
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The Plot to Save Socrates
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