This is more or less what I felt happened... Copy & pasted from somewhere else... Theory No. 1 (and the one I prefer): Chase is using the final scene to place the viewer into Tony's mindset. This is how he sees the world: every open door, every person walking past him could be coming to kill him, or arrest him, or otherwise harm him or his family. This is his life, even though the paranoia's rarely justified. We end without knowing what Tony's looking at because he never knows what's coming next.