Well, actually it's pretty commonplace nowadays to have heavy spoilers in the back-of-the-dvd-case texts as well as in the dvd-menus. Just take 'Equilibrium' or 'Matrix Revolutions' as an example, I'm sure you can find plenty of dvds that give away important plot turns/surprises on the back of the case or within the menu.

Although I have to say, that Lucas Marketing really topped everything by minimalistically mentioning spoilers-only on the dvd case. Congrats for another #1 shitlist award to Lucas Marketing.