Well John Gardiner, whose book THE ART OF FICTION is a favorite of mine, used to talk about not waking the author from the "dream" of the story, and this book, while not new, and while a good rousing tale, contained several "wake up calls."
Looking at if from a writer/craftsman's aspect, it seemed fairly obvious to me that the author had conceived it first as a modern story, then set it back in time. There was a wonderful wedding scene. It had whole roasted pigs, jongleurs (what the hell is a jongleur, anyway?), lute players and troubadours singing bawdy songs of wedded bliss. Then a minor character praised the cheese served in the wedding "buffet," saying to the bride's father, "Where did you get this wonderful cheese?" To which the bride's father replied, "Oh, I'm glad you like it, okay? We had it flown in special."
"Buffet" and "okay" would have been bad enough, as in Elizabethan times "buffet" was a cupboard and "okay" didn't come into usage until the 19th century and then only as an American expression until the 20th. But "flown in?" How?
This is why it's important to have your own set of first readers, trusted friends who will go through your manuscript and warn you about things you may have missed. One of the best things about writing is that you can so easily go back for "do overs."