The glyph/code spells out WINDOW.

Science Center Worker: May I help you?
Astrid: Yes, uh, I'm looking for someone who seems to have gotten lost.
Science Center Worker: Okay, what school is he from?
Astrid: He's not from any school. He's a man. His name is Dr. Walter Bishop.
Science Center Worker: Hmm, I see. A special needs individual.
Astrid: Heh, you have no idea.

Walter: When the Victoria, the last surviving ship, return to its harbor of departure after the first circumnavigation of the earth, only 18 of the original 237 men were on board.
Small Child: What happened to them?
Walter: They all died, young lady. Horrible and most likely painful death. You see, when you open new doors, there is a price to pay. Now imagine... tonight, you look under your bed, and, lo and behold, you find a monster! And you're immediately eaten. Now, if you hadn't looked for the monster, you wouldn't have found it and you'd still be happy in your beds, instead of being slowly digested in the stomach sack of the creature. But, with any luck, your sister or your brothers might have heard your screams, and your endeavor will serve as a valuable lesson to them.

Walter: Take me to your centrifuge.

Peter: I'm sorry.
Olivia: You weren't yourself.
Peter: It's lucky for me that you were.

Astrid: Walter. Um… inside… upstairs… when you said, "I can't let Peter die again…" what did you mean by that?
Walter: Some things are meant to be left alone, Agent Farnsworth.

Dr. Bishop states that the rabies virus cannot survive in water, and thus the virus causes its infected host to fear water -- citing it as an example of a virus manipulating its host's behavior. This is false, and is based on an incorrect understanding of hydrophobia, a late-stage rabies symptom. Hydrophobia in this context refers to the fact that, as the disease progresses, the infected person's throat becomes paralyzed to the point where the inability to swallow causes panic, possibly because it induces the feeling of drowning.

The Observer is behind McFadden as he tells his assistant to call the State Department.