“This error,” they say, “which was not identified during peer review, is that the radiocarbon dating was applied to soil samples that were not associated with any artifacts or features that could be readily interpreted as anthropogenic or ‘man-made.’
It definitely should have been flagged up by peer review (I've done it for dating studies with a far better scientific grounding than this) and might suggest the authors were deliberately obscuring the information or the journal's review process is woefully inadequate.