The argument Charlie makes about Chelsea keeping her apartment as a kind of "liferaft" for the relationship is the same argument Woody Allen's character uses in Annie Hall (1977).
The title makes reference to Sir Lancelot du Lac, a French knight who was King Arthur's right hand man and dear friend and ran away with his queen, Guinevere, during the legendary times of the Knights of the Round Table.
Episode title spoken by Chelsea (Jennifer Taylor), to Charlie.