Selected
Laura Poitras is "selected" to document Snowden's journey. The selection is a symbol that she has experienced the same hardships that are results of spying practices on private citizens which Snowden is set to release to the public.
Metadata
Metadata is the collection of call length linked to specific numbers, combined with credit card purchases, metro pass swipes, et al. This data creates the ability for security agencies to speculate as to who could be a terrorist. Thus our metadata becomes a speculation which intelligence agencies are using as definitive evidence as someone being involved in terrorist activities, when in truth this metadata cannot technically produce that fact.
Search Engines
Because of NSA spying, people are cautious of what they type into a search engine, especially in particular parts of the world for fear of being detained. This is a symbol of the fear-mongering that has been created by the NSA which limits people's right to learn and grow. And, for fear of being detained they don't even use the internet search engine to search things they desire to learn.
Family Ties
Snowden exposes the NSA and chooses not to tell his girlfriend and family. This is a symbol of ensuring they no nothing at all of what he has done so that they do not get caught up in the investigation and become suspects.
The Guardian
Snowden uses The Guardian, a reputable newspaper in order to release what he has found from the NSA. This is a symbol that he wants to ensure his message is received and verified in a way that is not bias, as he knows he has strong opinions about what is happening.