Large panoramic pictures like this involve moving the camera all over while taking lots of pictures. While a shot like this is being taken, time continues its inexorable march. That guys face happens to be on a boundary of two of the pictures that made up this giant composite, and in between the shots taken of that part of the image, he moved his head.
You can likely find quite a few more such anomalies in this image.
Like Street view in Googleearth.