Kate referring to Barbossa as "Uncle Hector" has been bothering me for a while now, and I finally realized what it is. As a Jane Austen fan, I have this on automatic recall — so, all of the PoC stories are set somewhere around the late 1700s, early 1800s. In those times, there were detailed how-to-properly-refer-to-someone rules, which meant that you referred to uncles and aunts as "Uncle/Aunt LastName" not "Uncle/Aunt FirstName."

Of course, I'm not sure if there's any point to counting the historical inaccuracies in this story.