It's interesting to think about, but I have to say that at first glance Occam's Razor is against it. The simplest and best explanation is that the cat was either dead or alive before we opened the box, and that opening the box was not an act that defined information, but simply revealed it, as most humans would assume. In other words, a game of War is determined entirely in advance by the shuffle of the deck, although the information may appear to be new to the players.

There was a time when I would've embraced this kind of theory of alterable reality, but the beliefs that I've developed over the past few years lead me to believe in the concept of truth being unalterable. Once something is done, it will forever be true that it happened, beyond the beginning and ending of all things.