I would totally not be surprised at all if they put the porn thingy in the box themselves, to give EA and/or Walmart a bad name. Kinda like that finger in chillli business a while ago, that was framed as well.
I found some games at my workplace that were obvious resealings, but they were shipped in from a distributor. SO I wonder if it's companies reselling returned games, or just some packager decided to play a prank.