Elizabeth Bennet assuming Amanda's surname is Spencer because of the label in her underthings references the scene when Lorraine thinks Marty's name is Calvin because his underwear have a Calvin Klein label.
The theme music is the ringtone on Amanda's mobile phone. She later tells her mother Frankie that she doesn't sit at home with the pause button on Colin Firth in clingy pants.
Lydia's joke that the Bennet girls "might as well take the veil" references the 2005 film, in which Mr. Bennet jokingly suggests that Lydia is "going to take the veil."