"The Observer" can be seen at back when Mark Young exits from the elevator at the beginning.
From a street sign, one can see that Massive Dynamic is located on Bell Plaza, obviously named for William Bell - the founder of Massive Dynamic.
Olivia looks at an airplane ticket during her investigation. The carrier is 'Oceanic Air', the same air carrier in creator J.J. Abrams' show, Lost (2004).
The glyphs in this episode spell "Voice".
Olivia makes a call and pretends to represent a long-distance carrier. This took place at a time after anti-trust suits had broken massive telephone monopolies, granting other companies to lease long-distance phone services at competitive rates from the former Bell telephone system. Although telemarketing by long-distance companies had greatly receded by the time of this TV series, such nuisance calls were still fresh in the minds of consumers, who had a long habit of saying no. One might also note the respondent's request to take their name off the "list". This was shortly after a law was passed compelling telemarketers to comply with "do-not-call" lists.