Mostly there are two issues. The first is a slightly continuing problem involving the central character, Jamie Waterman, a half-Navajo geologists. While the character was raised in Berkly, he spent summers with his grandfather who ran a store on the Plaza in Santa Fe.
I have no problem with the idea that a Navajo would run a store in Santa Fe, I've met at least one who at least worked in one - he joked with me that the rug depicting Pepsi trucks was authentic since they had Pepsi trucks before the coming of Europeans. But Bova keeps making mistakes with the Navajo culture and history that I, most of whose knowledge of these issues comes from the works of Tony Hillerman (which were acknowledged and praised by the Navajo Nation, IIRC), and quickly spotting.
Perhaps the most glaring was in the first book where he had some flashback scenes where Jamie and his grandfather are visiting a Pueblo so his grandfather can buy artwork for his store. The problem is that the Pueblo is indicated to be Navajo. But the Navajo are not Puebloan. There are great cultural and even genetic differences between the Navajo and the various Puebloan groups in the area.
In the second book, written several years later, Bova fixes that, but then goes to make a greater error. In the opening section, he depicts Jamie rushing across the Reservation to the hogan where his grandfather lays dying. But in the following scene, the grandfather is laying in the hogan with another Navajo. The stories make it clear that Jamie's grandfather was more or less a traditional Navajo, so the last thing he would want is to die inside any structure. Any structure where someone dies becomes uninhabitable (which Bova does acknowledge, but misses how this is handled), and would if fact have a large hole cut out. Instead a traditional Navajo knowing they were about to die would be outside, possibly under a shelter.
In the same scene he also mentions blinds across a window in the hogan. If this were truly a traditional hogan, not a house on the reservation, it would have only two openings: the door - facing east - and the smoke hole for the fire.
On the other hand, Bova does seem to have a decent grasp - or at least as good as mine - on some of the basics of the Navajo religion and myths.
The other problem came from Bova's descriptions of Olympus Mons. Both Bova and his characters kept comparing it to Mount Everest and how high Everest raises above Sea Level. But the more accurate mountain on earth to compare it to is Mona Loa.
While Everest is the highest above sea level, its base and even the flatlands on both sides of its range, is actually above sea level. Mona Loa doesn't rise as high, but its base is at the bottom of The Pacific Ocean, well below sea level. Since Olympus Mons rises from a plain, and sea level is meaningless on Mars (at least in the current era) the comparison should be made from the actual bases of the mountains, where Mona Loa has Everest beat, by a fair amount if I recall.
The other reason I'd use Mona Loa instead of Everest is that Olympus Mons and Mona Loa are similar mountains - both shield volcanoes, where Everest is an upthrust mountain.
Now, since most readers don't automatically know that Mona Loa is the mountain that rises the furthest from its actual base, I can understand having some references to Everest as well. But Bova could have had the characters, many of whom are geologists or at least scientists who should have also studied geology - at least to make sure that they understand each others work - some of their statements and thoughts could have made the more accurate comparison.
I'm not sure why these keep striking me. I'm half-guessing that it is because I'm otherwise finding this a good book so the minor rough patches are more noticeable. The other possibility could be akin to how Tara will notice mistakes in lab and medical procedures in TV shows that I miss, where I'll notice - at least until they get too ridiculous to worry about - computer related mistakes: I'm noticing the mistakes since I have better knowledge than other readers/viewers in a couple of areas.
In the first case, I may also be noticing since I think that a bit more research could have resolved these problems.