Marcus' stepmother's title would not be 'Duchess Beaton' as in the United Kingdom, ducal titles are generally Duke of X, and the holder's last name is completely different from the title. For example, the current duke of Wellington's title is Arthur Wellesley, Duke of Wellington, not Duke Wellesley. Although it is not mentioned in the show, Marcus' title of Lord Marcus indicates he is a younger son, otherwise he would likely have a courtesy title as his father's heir.
At the end of this episode after Catherine gives Nate an envelope in the limo, a take of NYC from a helicopter is shown. If you look carefully you can clearly see how the cars on the street move "backwards". This scene was taken in the other direction.