One of the notes in the big pile of tubes mentions a person called S.R. performing an activity in the Swan station; this is most likely Stuart Radzinsky, the designer of the Swan station, who worked inside the Swan at the time (which is confirmed in the same episode by Kelvin Inman).
After Desmond is released from military prison and dishonorably discharged from the Royal Scots Regiment of the British Army, Penelope's father reveals Desmond's last name when they have a talk in the limo. Desmond's full name is Desmond David Hume. David Hume, like John Locke, was an important philosopher of the 18th century. Hume was a Scotsman, just as Desmond is (hence he was in the Royal Scots Regiment). Both were Empiricists, and Hume was heavily influenced by Locke. This would serve to explain the friendship between John and Desmond on the show, and why Desmond goes along with John's plan to stop pressing the button without having seen the Pearl Orientation tape. It appears the show's writers have a habit of naming characters after famous philosophers in history. Rousseau is named after Jean-Jacques Rousseau, also of the 18th century, a French-Swiss philosopher of the Enlightenment whose political ideas influenced the French Revolution. Fleeing criticism in Switzerland, Rousseau took refuge and lived with Hume in Great Britain for a time.
Throughout the series, Desmond habitually refers to male characters as "brother" (as in, "See ya in another life brother!"). This episode marks the only time he addresses a female castaway (Claire) as "sister."