Having not seen the picture in the flesh (so to speak), in common with almost everyone else, it is very difficult to say whether, as Damien points out the rear fuselage is slab sided, or that is a trick of the light; what can be said is the front end including the wings and wing fairings look good, and that would be the hard bit to get right,so if it is an actual fault in the workmanship, one might expect the front end to have suffered as much if not more.

As an aside, I have several paintings of Spitfires (appropriate point to gasp), and even the master Ronald Wong has got a few details wrong; the best of the rest, is by Phil Arbles (if I have got his signature correctly deciphered) , I am told that he used to do the art work for one of the plastic kit manufacturers (possibly Airfix)