A couple of art inaccuracies that I remember are Sulu in a blue uniform shirt on the cover of Shadow Lord, and a large sword being prominently featured on the cover of Captain's Honor despite no sword being featured in the novel at all.
There are also plenty of New Frontier
novels with swords on the cover, even though there aren't any in the books. It's not inaccuracy, it's symbolism. Not all art is literal. (Although in the NF case the sword represents the starship Excalibur
. On The Captain's Honor
, it presumably symbolizes the ancient martial traditions that drive the Magna Romans.)
I made my previous statement regarding Captain's Honor
in regards to the sword after reading in Voyages of the Imagination
that David Dvorkin, the co-author of the novel, didn't see why the sword was on the cover. He also made mention of the fact that the sword looks much more like a Japanese sword as opposed to anything the Romans used. (I make no claims to being an expert on ancient cutlery but I agree with him on that.) He also makes the point that the likeness of Captain Seljanus on the cover doesn't really mesh well with the description given in the book. I am well aware that symbolism is often used in art but I prefer to take my lead from the book's author on this point.