First appearance of Dr. Mark Sloan (Eric Dane).
Dr. Mark Sloan is supposed to be the same age as Dr. Derek Shepherd and older than Dr. Meredith Grey. In reality, Eric Dane is 6 years younger than Patrick Dempsey and 3 years younger than Ellen Pompeo.
In this episode, the patient with lionitis is played by Jesse Plemmons. In the previous two episodes ("It's the End of the World" and "As We Know It"), the bomb squad leader is played by his Friday Night Lights costar Kyle Chandler.