Bathtub
After a full day of traveling through Manhattan searching for food and supplies, working out and dinner with Sam we see him and his companion huddle into their bathtub as night falls. The image is a stark contrast to the sunny day they've just had together. It shows us that though this is a man that can handle himself in extreme circumstances he still has very human emotions as he is afraid of what comes once the sun goes down. And like any normal person he's terrified of being discovered and killed and this image shows us all of that.
Last Line of Defense
In the basement at the climax of the film Lawrence shoots Anna and Ethan on one side of Robert and the infected on the other side of him with only glass between Robert and the infected. The image brings to conclusion Robert's journey, specifically when he rushes the glass to collide with the infected male as the grenade goes off. The imagery shows us that Robert in these final moments is in between life and death both figuratively and literally. He could choose to go with Anna and Ethan but knows that they will be chased down, and he also knows that the antivirus must get into the hands of other people to save mankind. Thus he must make the ultimate sacrifice in order that others might live and the composition details this.
Flashbacks are Chaos
Whenever Lawrence flashes back to Robert's memory of the day his family is killed he uses an unstable camera and we see a lot of action from a tremendous amount of people. By doing this in these scenes he's able to starkly contrast the feeling of isolation that Robert is now experiencing with the chaos of that final day with his wife and daughter. We are able to see how both feel unsettling, but for completely different reasons.
Butterfly Crack
As the infected man charges the glass in order to break through and kill Robert, Anna and Ethan the glass begins to crack. As it does it splinters out into the form of wings. This imagery relates thematically to Robert's journey of faith and believing in the signs that are right in front of him. Seeing these wings becomes a catalyst for his faith to be activated when he sees Anna's butterfly tatoo which triggers his daughter's voice in his heart.
