Other mistake: When the group is in Wilmington, before going to see the dead whale, they run into Duff, a shipmate of Roger's. He introduces everyone, introducing Marsali as 'also Mrs. MacKenzie.' He should introduce her as 'also Mrs. Fraser,' since she is married to Fergus Fraser.
Continuity mistake: In chapter 22 Claire wakes to find Brianna in the kitchen with a teething Jimmy and offers to take him. She walks to the malting shed in search of whiskey and spots Jamie praying and now it's the end of the day. Did it take all day to get there? Did the child not need to be fed all day?