"The Observer" can be spotted near the elevator in the beginning.
The glyphs translate to spell the word "Surge".
Though the episode's intended commercial break glyphs were originally aired to spell "SURGE", on the US bluray boxset copy (2008/2009) of this episode, the last glyph inappropriately shows a "second G", resulting in the episode's glyphs to mistakenly spell "SURGG".
The establishing shots for the office building in Worcester are actually of downtown Hartford, Connecticut.
Walter Bishop remembers that Astrid's name begins with an "A", thus beginning the constant in-joke is the series of Walter not remembering her first name, yet remembering her last (or just taking the piss with her as it's revealed and established much later on).