Everywhere a Prison
Rosenberg uses doorways in the film as entry points from one prison to another. We see the men in the bunk get pushed out of the doorframe by Carly to the mess hall. The image shot from inside the empty bunk shows the door frame closing them in even as they exit outdoors. Thus the door frame creates a feeling of claustrophobia, the same feeling the prisoners feel in the prison.
Fan
Before Luke fights Dragline, Rosenberg sends the camera into a spinning metal fan. The imagery shows that the showdown with Dragline is going to be one that is not going to end well; we feel this ominous sensation with the spinning of the metal blades closing down on the frame, before Rosenberg cuts to the men outdoors boxing each other.
Stay Down
Luke is knocked down again by Dragline, and as he is on the ground he sees the chains on the feet of another prisoner. The image shows us that if Luke stays down he is a prisoner chained by the fact that whenever he gets knocked down he stays down. It shows why Luke gets back up...he desires freedom in everything he does.
Stop Sign
After the men complete tarring the road with two hours of daylight to spare, Rosenberg dissolves from the men into the bosses and a stop sign. The imagery shows that what the men have done has penetrated through the guards and in a sense changed the way they look at the prisoners for better or worse.