In the hospital after Dean punches the glass, "code grey" is heard on the overhead speaker. Code grey is a common code in many healthcare facilities for a combative person.
Per an October 2014 interview with TVline.com, celebrating the 200th episode of the show, Jared Padalecki states 'Death's Door' is his favorite episode of the series thus far. Jensen Ackles revealed that it's also his favorite episode as well.
Bobby is pushed into the trauma OR and a Dr. orders 80 grams of mannitol. Mannitol is a sugar alcohol. It is used to treat cerebral edema, and this gets a bit complicated. If you sprain your ankle you take off your boot and the ankle has room to swell (edema). If your brain swells, there is no extra room in the skull and the pressure can kill your brain. Edema is extra water in tissue, if you could draw the extra water from a swollen brain that would be good. Manitol does not readily leave the blood to enter brain cells (blood-brain barrier) so mannitol in the bloodstream draws water out of the brain tissue and into the bloodstream (osmotic diuretic). It is a standard short term treatment.
This episode was originally titled "Not Fade Away", the same title as the series finale of the show Angel (1999) - Not Fade Away (2004).
When Bobby is brought into the hospital one of the healthcare professionals states "GCS 5". This is in reference to the Glasgow Coma Scale(GCS) which refers to a patients level of responsiveness in relation to their alertness, verbal response, and mobility response. A GCS of 3 is completely unresponsive.