At around 41:25, when Jamie is telling Jenny and Ian to turn him in for the reward money, the "green screen" special effects stocking that Steven Cree wears (to hide his real leg and give the allusion that he is an amputee with a peg leg) is visible under the table when he enters the shot.
Fergus is played by the same boy who played him in the second season. However most of the plot happens 6 years after Culloden when Fergus would have been about 16, not 10 or 11.
The guest at the dinner table alludes to his wife's sexual prowess and they laugh it off. Such a comment would never have been made in that day at the table of a middle-class couple, much less when the guest of a Harvard professor. It is such bad taste that it would not even be made today, much less in 1949.