I've been checking art and text while cataloguing. Sometimes, the image shown by deckbox shows different flavor text than both my card and the image on Gatherer. It's happened with somewhat newer cards - Tarkir, Origins, Amonkhet, Hour of Devastation - but not older cards so far. So I've been able to easily confirm the card number and correct expansion.
I trust Gatherer more than deckbox, so I'm wondering why the deckbox images sometimes don't match? Should I mark the cards as altered art in those cases? Or is it reasonable to keep trusting Gatherer?
On a similar note, I got a copy of The Scorpion God from the Hour of Devastation Prerelease box and it has a date printed/embossed over the lower-right corner of the art which isn't shown in either the deckbox or Gatherer images. Is this typical for prerelease cards and does it affect the value? Should it be marked with the altered art flag?