I think these shines would help explain the volumetrics of the plane, seeing as it is in open daylight and the heavy right bias to the lightsource doesn't make much sense, but also it makes especially the hull of the ship look as if it's a bit 'gradiented'. However, the shines I added outline a problem with the main hull and jet engines in relation to the wings.. they seem to have a bit of a mismatched perspective. I didn't edit to that extend because it would mean extensive reworking. In fact, my shined edge on the beak of the ship accentuated the problem that was 'hidden in the shadows' before, sadly. Perhaps setting up a rudimentary 3d model beforehand of pixelling would help, if you've got the faculties for that.
I added the yellow tint to the actual exhausts that emmit the flames, I thought it would be strongest there than on the reflections in other places.
I defatted the black line on the far wing, again a matter of preference, I think it looks better thusly, personally.
Fixed a really small nitpick on one cloud.
I 'showed' a bit more of the far turbine since given the volume and angle of the hull, I don't think it could be obstructed as much as it was.
This is really nice, I think if you adress small points such as these you can get it to be as good as it can be, without major reconfiguration of perspective.