Im aware of the film on the cards, but I was talking about the ones with the trees on them. I think the level 2 show a red tree and the level 1 show a green tree.
There is definitely a colour difference. I will try to get a picture on here. If these are cards that you draw throughout the game it might be a big deal because this colour difference would tip you off as to what was coming up next. If it's a case of drawing some cards at random during the game start and leaving them out then it wouldn't be a big deal.
I just opened my expansion box and noticed a color difference there as well. On the plus side, if you end up with 3-4 different shades that is almost as good as a single constant color right?