In "Dr. Sexy M.D." there is a character who, according to Dean, is a ghost in the mind of one of the doctors. This seems to be a reference to Denny Duquette from Grey's Anatomy (2005) who was played by Jeffrey Dean Morgan who also played Sam and Dean's father, John Winchester in "Supernatural".
The name of the show that Dean watches in the beginning and that both Sam and Dean find themselves inside of later, "Dr. Sexy, M.D.", originated in an earlier episode. It was mentioned in an offhand remark in The Monster at the End of This Book (2009) by "Carver Edlund's" (a.k.a. Chuck Shurley's) publisher, who tells Dean and Sam "all anybody wants to read anymore is that romance crap- you know, 'Dr. Sexy, M.D.'? Please."
When Sam and Dean are on Dr Sexy MD there are several references to Grey's Anatomy (2005) including 1) the background music which is a huge part of the show 2) the name of the hospital is Seattle Mercy like the original name Seattle Grace which was then Seattle Grace Mercy West 3) Dr Sexy is a neurosurgeon just like Dr McDreamy on Grey's 4) there is a character with the name of Ellen like Ellen Pompeo 5) there is a neurotic doctor in love with a ghost who was played by Sam and Deans father 6) there is a cardiovascular surgeon that mimics Cristina Yang.
When they are in the police procedural drama, both brothers are obviously imitating David Caruso in CSI: Miami (2002).