This is an excellent map. The colors are truer than nature, the subtle shadow/light play is fitting, Mars portrait is nicely stylized.
I would just adapt 2 things - both have been mentionned.
- Terra could be more bluish/greenish and Luna more whitish/blackish to suggest the true colors of those bodies all the while keeping the general rusted tone.
- There is no reason for the polar caps to be semi transparent. Either they were planned and then they are behind the frame. Or they have been added after the map was done and then it is them who override the frame. Doing both is perturbing (at least for my eye).

Third is that the river Isis is physically improbable - the blue suggests water and the idea of a continuously decreasing altitude on a track going over half the planet's perimeter shouldn't happen. But it is perhaps a feature that exists in the comics, I don't know.