The song Claire sings is based on the "Boogie Woogie Bugle Boy of Company B", which was performed by The Andrews Sisters, and was also a popular song during wartime in 1941.
This is the only episode in which Sam Heughan (Jamie Fraser) doesn't appear in the entire first season.
Seorise tells Claire that you can't own words. In fact, the British enacted the first copyright law in 1710, some three decades before the episode.