Opening Shot
In the opening shot of the film, we see a car traveling down a dark tunnel with only strips of light above. We can't tell how long the tunnel goes on or what is at the end. This imagery represents the entire story we are about to experience as it is unclear how any of this will turn out in the end.
Calm
Poitras shows exteriors of the Hong Kong hotel Snowden is staying in before cutting to the interior of his room where the interviews are held. This imagery reveals the calm that is existing in the surrounding world, and the contrast between it and the paranoia and fear within the room where Snowden is symbolically trapped.
Visual Collection
We watch as Snowden covers himself with a red sheet while inputting information into his computer. This image shows us his acute understanding of the capabilities of the NSA to spy on people, to the degree that the NSA can see and hear you in a room anywhere in the world and know what you are doing.
ECU
Poitras shows an extreme close up of Snowden's hands and face while he is typing messages with his partner Lindsay, who is still in the U.S. The imagery reveals that this is the only connection he has to the outside world; he has lost his personal connection with those he loves and he feels it in an intense way.
