The glyph/code spells out SECRET.

Peter: I just got off the phone with Olivia, she said there was an incident on a train. And I know how much you like trains. Thought it might cheer you up.

Peter: Have you noticed anything weird?
Olivia: Not yet, but give it ten minutes.

Walter: Take samples of this man's lung, brain, and skin. Something's not right here.
Astrid: Yup, I think it's my paycheck.
Walter: Hmm?

Peter: Yeah, I read that deja vu is Fate's way of telling you that you're exactly where you're supposed to be. That's why you feel like you've been there before. You are right in line with your own destiny.
Olivia: Well, do you believe that?
Peter: Mm.. no. It's a bit mystical for my taste. I never get them, myself. Maybe that's because I'm not on track with my own destiny.

Carol Bryce: Alistair sent me these about six months ago to proofread. He had hopes of seeing them published.
Olivia: Uh, can we take them?
Carol Bryce: They're only gathering dust here. But they are pretty dense. Most would say it's gobbledygook.
Olivia: Well, I happen to know someone who is fluent in gobbledygook.

Walter: I, too, attempted the unimaginable, and I succeeded. I crossed into another universe, and took a son that wasn't mine. And since then, not a day has passed without me feeling the burden of that act. I'm going to tell you something that I have never told another soul. Until I took my son from the other side, I had never believed in God. But it occurred to me... that my actions had betrayed Him and that everything that had happened to me since was God punishing me. So now I'm looking for a sign of forgiveness. I've asked God for a sign of forgiveness. A specific one: a white tulip.

Alistair Peck: Walter, God is science. God is polio and flu vaccines and MRI machines, and artificial hearts. If you are a man of science, then that's the only faith we need.

The Observer can be seen in the background just as the car hits Alistair and Arlette.