When Sybil and Branson decide to elope, they go to Gretna Green, a village on the Scottish-English border that is about 100 miles northwest of Downton Abbey (which although fictional, is set near Ripon, Yorkshire). Beginning in the mid-18th century, Gretna Green became a popular location for runaway weddings because of Scotland's lenient marriage laws, as it is the first village on the Scottish side of the border along the main route from England. In 1754, legislation was passed in England and Wales to prevent elopements: Minors under the age of 21 needed parental consent to marry, Christian weddings must be done in a church to be valid, and a public proclamation of the marriage (known as banns) must be made to allow time for anyone to object. Although Sybil was already 21 at this time, applying for a marriage license anywhere near Downton would have alerted her father to her plans.
Theda Bara is one of the first movie star mentioned by any of the Downton characters. Before this Ethel mentions the movie star Mabel Normand.
The episode won an Emmy Award for Outstanding Music Composition for a Series (Original Dramatic Score).
The song Mathew plays on the gramophone he attributes to a failed play called Zip Goes A Million, that was based upon the 1902 book Brewster Millions (later made famous by the film starring Richard Pryor). The play debuted in the USA in late 1919.