Yeah, you are right, Nick. Also, over the course of the movie, his face changes too, which makes it difficult to nail the likeness when you are using reference from different parts of the movie. I like the way he looks when he's delivering the "That Terminator is out there..." speech, but he looks more gaunt in his face than, for example, the scene where he and Sarah spend the night under the bridge. I imagine one was filmed toward the beginning of the shoot and the the other toward the end when he had lost a few pounds.