The first recorded instance of guising, or dressing in costumes and collecting treats, in North America wasn't until 1911 in Canada. It didn't become popular and widespread in the United States until the late 1910's and early 1920's. As this is set in the 1850's, having the Boones dress in costume was 60 years too early.
Dr. Guilford proposes applying a "vitamin rub" to Loa's rickets-affected leg. The term "vitamine" (later "vitamin") was not coined until 1912, many decades after the setting of this story.