What is the advantage of the inverted image on the retina?
There may be no advantage of the inverted image on the retina. But there is an advantage with the lens that refractes the image inverted.

Our eye lens is of convex in nature. Now lets see what is the advantage of convex lens being our eye lens. 



Source : http://www.ivyroses.com/HumanBody/Eye/concave-and-convex-lenses.php

The light from the object, when reaches the convex lens it gets refracted and gets "converged" and is a "real image" and also "diminished" but the problem is it makes the light inverted.

Now let us see what happens if our eye lens is a concave lens.



Source : http://www.ivyroses.com/HumanBody/Eye/concave-and-convex-lenses.php

In this case, when the light from the object from a distance reaches the lens, the lens "diverges" the light, also it "enlarges" the image, but it produces an "erect" image but the major problem is that the image is "virtual".

We know how evolution works, it selects more advantageous option generally.

Case - 1: If the lens is convex, the only problem the eye has to handle is that the image is inverted.
Case - 2: But if the lens is concave, it should converge the diverged light, it should diminish it and it should also make it real.

If we take both cases into consideration, case - 1 seems to be easily handled, that's why we have inverted image falling in the retina. There maybe no other specific advantage associated with it.