Wow. I didn't even notice that. But correct versions of the poster do exist. I don't know when the different versions were produced. They both carry the same National Screen Service number (53/404) in what appears to be the same lettering. Out of 25 images of the poster that I've looked at on an auction site, only 6 were of the correct version, and only one of the descriptions of the 19 incorrect ones even mentioned the discrepancy. When MGM re-released the film in 1963, the re-printed posters (with NSS # 63/219) were of the incorrect version. The auction prices of the poster don't seem to be influenced one way or the other due to the error.
Thanks Bob. I have 53/404. It's amusing that, after they corrected the error back in '53, the 1963 poster reinstated the mistake. Unlike stamp collecting, it would seem that the correct posters should be the valuable rarities.