Error Cards

I have a few error cards that are fairly interesting. In searching through my old lots for Dodgers for Night Owl, I came across this pair of cards from '91 Topps:

But if you look at the back, their is not one iota of difference between the two.

A peak at Beckett reveals the answer: The one on the left is actually Billy Beane. It is worth five times what the actual Jose Gonzalez card is worth! Too bad that the actual one is only worth five cents. 

The other set of cards comes from this year's Topps Series 1 set. This is the first box of regular hobby cards that I bought after starting to collect again. Can you find the problem with these? 

 

Of course, there is no foil stamping on the cards of Rick Ankiel, Jeff Kent and Billy Wagner. I ended up with several dozen of these, including Ryan Howard. Topps requests that you send in the cards, the packs, the box, the reciept, a blood sample, a pound of flesh, some dirt from your yard, your tax returns from the last seven years and a picture of your wife in order to get the cards exchanged for corrected versions. I'm holding on to them for a while, just in case. 

What do you think? Are these "error" cards, or are they less than worthless?