When JD dances on his piano mat to play a quick tune, he plays the last few notes of the intro song where the lyrics go "I'm no superman." He then says "That's catchy."
JD talks to Denise about the "patient who died of lung cancer last Monday". This was in reference to the previous week's episode.
In episode 303 "My White Whale" Dr. Norris, played by Christopher Meloni, has a puppet named "Mr. Cookie Pants".