The glyph/code spells out LIMBUS.

Walter: Immoral, evil...
Astrid: Walter, we have been over this. What is in the past in in the past. We have agreed to move forward.
Walter: Even I don't have drugs strong enough to forget they kidnapped Olivia to the Other Side.
Lincoln: They did?
Walter: Two weeks that awful woman pranced around my lab.
Lincoln: Awful woman?
Astrid: Uh, the other Olivia, the one from Over There.
Walter: She bought my ignorance with baked goods while she carried out her plan to steal a piece of the Machine with that damned Portuguese sweetbread.

Olivia: What's with the redecoration?
Astrid: Walter. Hey, don't look at me like I have some reasonable explanation. It's Walter.

Astrid: (about Lincoln) Well, he just lost his partner. Plus he is new in town. He doesn't know anybody. He's probably a little lonely.
Olivia: No. Not going to happen.
Astrid: Why not? He's cute.
Olivia: Because if I went out with him, then I would start having second thoughts, like I always do, and then he would get hurt, and then my workplace would become awkward. And you know what? He's not even my type.
Astrid: Do you ever think that maybe your type just doesn't exist?

Olivia: He knows what she taught him, but he can't remember who she is. How is that possible?
Broyles: At the risk of sounding sentimental... I've always thought there were people who leave an indelible mark on your soul. An imprint that can never be erased.

As John confronts McClennan after the commercial break, an earpiece is briefly seen in McClennan's ear. It disappears in all subsequent shots.

The Observer can be seen at the hospital as Broyles and Olivia discuss how John has lost his memories.