My favorite detail about this construction is the way you used different physical densities to create a sense of distance. The way it goes from being 3D to flattening out in the background has an effect that makes this much more interesting to look at, and actually allows your eyes to dawdle over the details for more than just a passing glance. I do think this method of illusion could have been taken further, however. For instance, the ground that the amazon box man is standing on is not the same density as anything else in the foreground, even though it clearly should be -- at least in part -- a part of the foreground. I think if you take the variety of sizes and thicknesses of the objects and play up the idea of variant distances just a little more, you could have something that would get many more eyes to cling on and wonder at the 3-dimensional aspects of Marioland.