Carter: You set the tone, Morris.
This quote was used twice previously in the series, and has become symbolic of a point at which leadership passes to the Chief Resident. Dr. Morgenstern first said it to Mark in the pilot episode, "24 Hours," following Carol's attempted suicide. Mark then said it to Carter in the Season 8 episode "Orion in the Sky," when Mark leaves the ER for the final time. When the departing Carter says it to a clueless Morris in this episode, it may have been intended more as a joke. Morris is redeemed, though, in the Season 15 episode "The Beginning of the End," when Carter returns to County and says the same words to him again, this time in admiration.
In the scene at Ike Ryan's, you can see Greg Pratt eating a mozzarella stick. We find out in the Season 15 premiere, "Life After Death," that these were his favorite.
Goof: In the scene where Sam finds Steve's letter for Alex in the mail, Luka's address is clearly visible:
3577 Leonard Ave #200 Chicago IL 60501
The 60501 zip code actually belongs to Summit Argo, Illinois, a suburb about 15 miles from Chicago.
In the opening scene, Carter and Abby are at the construction site of the new clinic. As they are walking away, several portable toilets marked "Oui Oui" are seen in the background. Oui Oui Enterprises is an actual supplier of portable toilets in the Chicago area.
After 9 1/2 years, we finally find out why Weaver uses a cane: congenital hip dysplasia, a birth defect.
The title of the episode comes from what Pratt tells Lysander Martin: "Sucks to be the middleman." It also applies to Pratt himself; he is a resident, between intern and attending, and is trying to find his place.
Goof: When Carter asks Dr. Henry to take the parents to the family room, Henry says "Yeah, I think I remember the way." However, the family room hadn't been built yet when Henry was a med student at County (in Season 4).
The book on Abby's night stand, Rats, Lice & History, was given to her by her Secret Santa, Dr. Dubenko, two episodes prior in "Twas The Night."
Music: "O Holy Night," composed by Adolphe Adam (sung by Hattie Winston)
In this episode we find out that Chen's address is 273 West Cedar Drive. In reality, there is no West Cedar Drive in the city of Chicago.
Dubenko: You don't get in trouble for doing something in the patient's best interest.
Abby: Tell that to Dr. Corday.
Abby is alluding to Dr. Elizabeth Corday's illegal organ donation procedure, performed five episodes earlier in "Try Carter." The operation saved the patient but resulted in disciplinary charges against Corday that led to her resignation in the subsequent episode, "Fear."
Goof: In this episode, Goran Visnjic wore a boot to protect an injury to his left foot. It's visible in the opening sequence in the chair area.