Peter points out that phone call was twenty-one years ago: "She could be anywhere by now," he says, which cracked me up beyond measure. I keep picturing Peter pulling out a drafting compass and spreading it as far as it can go to represent the 21-year distance range on a map.
Anyway, apart from being near and dear to several people in the room, Olivia was also sent to retrieve an important piece of equipment that Walter needs to put together the resistance plan he and September worked out and then intentionally scrambled in Walter's mind so the Observers couldn't read it. "He told me that when the time came to implement the plan, I had to retrieve something from Grand Central Station, and that then all would be clear," says Walter, and that's what he'd sent Olivia to get. She was on her way back.
Walter -- still not wearing pants -- chews off a hunk of egg-stick before spitting it out in disgust and lamenting the state of this future, before tottering off and snapping at "Aspen" to come help him, while Peter does his best to assuage Etta's doubt that they're going to find Olivia. "If she's alive, we'll find her," he says. I imagine that makes Etta feel tons better.
Columbus Circle, we find out, is a burned-out shell of its former... glory? I don't know, I've never been there. Suffice it to say, Walter's not pleased by the corrugated steel walls covered in graffiti (including Believer iconography that makes it look like one of those street art things like Andre the Giant Has a Posse.
Peter climbs up to have a look past the barbed wire topping the fence, where he sees the park has been paved for a vast carbon-monoxide production facility. It seems Earth is too oxygen-rich for the Observers, so they're reducing the air quality for their benefit, Etta tells them, which is also reducing the average human life expectancy to forty-five years old.
Walter, growing agitated, says it was right around here where Olivia called from, before her call was abruptly cut off. Astrid points out a nearby building partially encased with amber. As the team makes its way there, Walter explains to Peter that Olivia did have her own amberization device, which they planned to use rather than be captured by the Observers. Walter bitterly tells Peter he'd have given Peter one too if Peter hadn't "abandoned" them. This earns a rebuke from Astrid. "He didn't mean it," Astrid tells Peter. "Sure he didn't," says an unconvinced Peter.