At the spot, where Miller is, there is a couch and a lever.

When I use the lever, sounds of something moving are heard, but I can't see anything moving and also when I run around the complex, I don't see anything changed.

Is it just for a show, I is there actually something that is opening/closing?

(similar to another hideout of Miller's men, where was an arena, there were huge doors, hydraulic, and I found a set of levers connected to it, while I couldn't get to the mini room with the levers, I could reach them through an opening... again, when I clicked "use" (E) I could hear sounds like the gate is opening, but the gate did not open.

For a second time, the levers did not react at all. (also, what a damn maze, finding a way out was harder than killing those mongrels)