Aloha, I was just looking through my 52 set, (something I never tire of) and noticed that the cropping on #28 Priddy is different on the black back version and the red back version. There is a window looking rectangle in the top left portion of the card that is chopped in one and not in the other.
Whenever I talk of 52's I like to point out that Zernial #31 has position listed on back as "ontfield" in both back color...never called or identified as an "uncorrected" error. Aloha, dave