The glyph/code spells out UNITES.

Peter: Walter.
Walter: Peter. You're up early.
Peter: Oh, no, I'm still asleep upstairs in my bed. You're just talking to an astral projection of me.
Walter: You're just saying that to see if I'm high.

Peter: Who's that at two in the morning?
Walter: Oh, my pizza.
Peter: So you are high, then.
Walter: Maybe a little.

Olivia: I understand that you had a visitor last night.
Roscoe Joyce: I don't remember talking to him, but I remember that he was here. It's a curse not remembering a miracle.

Peter: Walter, are you all right?
Walter: If all right means despondent, yes.

Walter: You know the future. Tell me how I can save my son from dying.
The Observer: There are things that I know. But there are things that I do not. Various possible futures are happening simultaneously. I can tell you all of them, but I cannot tell you which one of them will come to pass. Because very action cause ripples. Consequences both obvious and unforeseen. For instance, after I pulled you and Peter from the icy lake, later that summer, Peter caught a firefly. I could not have known he would do that. But because he did, a young girl three miles away would not. And so later that night, she would continue looking, trying to find another one. I could not have know that when she did not come home, her father would go looking for her, driving in the rain. So that when the traffic light turned red, his truck skidded through the intersection at Harvard Yard, killing a pedestrian.
Walter: Did that happen?
The Observer: You and I have interfered in the natural course of events. We have... upset the balance in ways I could not have predicted. Which is why now I need your help.

Roscoe Joyce: I forgot what my son felt like. What he smelled like. How it felt to be around him. But now I remember. Nobody is supposed to have a second chance like that.

Peter: First he saves the girl, then he tries to kill her. Then he runs up five flights of stairs just to shoot me with his magic air gun and disappear. None of it makes any sense.
Olivia: And how is this different from any other day?

Peter: You ever feel like every time we get close to getting the answers, somebody changes the question? Olivia.
Olivia: So why is this your favorite book?
Peter: Because it talks about not depending on other people for answers. That you can only find the answers inside yourself.

The stuntman filling in for Joshua Jackson during the air gun "stunt" is clearly not Joshua Jackson: his hair is noticeably lighter.

Walter: These were created by an old friend of mine. Dr. Jacoby of Washington State.

This is a injoke to Twin Peaks. Walter is wearing the same glasses as Dr. Lawrence Jacoby, the psychiatrist on the TV series Twin Peaks.

Peter: Walter's channeling the Amazing Kreskin.

Kreskin is a mentalist who can "cold read" people by observing body language and watching for psychological "tells." He also claims to be able to foretell the future, making annual predictions.

Olivia: I feel like Rip Van Winkle.

Rip Van Winkle is the title character in Washington Irving's 1819 short story where a man goes to sleep for 20 years and has to cope with how his town has changed after the American Revolution.