The glyph/code spells out LIVING.

Stephen Root and Romy Rosemont are real-life husband and wife.

Olivia: Where'd you disappear to?
Peter: I was checking up on Walter. He found the swing set. You know how he feels about Newtonian mechanics.

Peter: There's only one way in. We need a Faraday Cage. It's got to be mobile, something that can block out the electromagnetic field. I can cross through and turn off whatever's causing this.
Olivia: Walter, you need to build a movable...
Walter: I heard the idea. I know what a Faraday Cage is! A baboon would! Astrid! I need a computer battery. And a spool of copper wire. And a climbing harness. And, and, some rubber cement. I think it's in my Spider-Man fanny pack.

Astrid: Here. Walter calls this the Walter Bishop Faraday Harness. He wanted me to tell you that.

Olivia: Just so you know, there'll be an FBI agent stationed out the front.
Peter: Where I would run to? So hey, do I get an allowance?
Olivia: I'll see what I can do.

Olivia: I was important to you, wasn't I? I mean, the other version of me. 'Cause I see the way you look at me when you think that I'm not aware.
Peter: Yeah. Yeah, she was. She is.
Olivia: Well, I hope that you get back to her.
Peter: Thank you. Me too.

Peter: What is a time loop? Like, Groundhog Day?

Groundhog Day (1993) features Bill Murray as a weather reporter trapped in a town where February 2 keeps repeating over and over for him, and he's the only one aware of it.

The Observer can be seen at the lower right in the first shot of Anne and Samantha's apartment.