When Luke is leaving Lorelai messages on her answering machine, he states his phone number is (860) 294-1986. This phone number actually goes to "Luke's" real-life brother-in-law, George Dover, who is the Director of the Children's and Maternal Hospital at Hopkins in Baltimore. People who call "Luke" reach George, who then asks for a donation to the children's hospital.
The song Rory picks to be her and Dean's song, "Candy Man", is from the movie "Willy Wonka and the Chocolate Factory". This was the movie that the two watched on their first date when Lorelai invited Dean to movie night.
The episode title is a reference to the Henry James novella 'Daisy Miller' in which a young American woman vacations in Europe, but whose flirtatious nature gets her into trouble. Rory also says "Say goodbye to Daisy Miller" in a conversation with Lorelai.
The beginning of this episode is supposed to be the same night as the last episode but Dean had a beard in season 4 ep 22 and is clean shaven in season 5 ep 1.