"Sales" in that reference means unit sales to retailers, not retailer sales to regular customers. Retailers ordered a lot of SR toys before any buzz whatsoever, so even if a single toy didn't sell Mattel's statement would still be true.

BTW, Target has their own Superman Returns Mattel figure exclusive now, it's a silver Superman, but completely silver head to toe, and the card insert doesn't have a title, the section is blank. He's sporting a plastic cape I believe (I didn't buy him, only scoped him at Pasadena Target for a moment).