A little late to the party, but the clear tell to me is the top border. It's as smooth as a Brazilian wax, when it should have all sorts of discernible bumps/pockmarks across it, most especially in the top right corner. There is 'always' a black protuberance (that's a ten cent word!) appearing there. Here are a couple of random scans showing what I mean...
1966mantletopborder.jpg
The other notable anomaly is where the black hits the red "Yankees" banner. It is never a perfectly smooth transition from black to red across that top border. Never. It should be jagged.