When Maximus goes to see the body of Caesar, the camera is facing him, and in the bottom left corner is Caesar's head. Just as you see his head, his eye closes fractionally. "He's not dead, he's just sleeping." Sure.
This is a pretty common slip-up when the camera is close to the face of a dead person. Usually you will see the eyball moving around a little bit behind closed eyelids. I see this all the time on TV on shows like CSI where there are closeups of corpses.