Robert Forster as Mac's friend, retired FDNY Chief Joe Vincent.
General:
Many family members of those lost on 9/11 appear in the memorial dedication scene.
Adam is revealed to have slept thru the 9/11 terrorist attacks.
Adam and Lindsay both worked the "bucket brigade", though apparently not together as they didn't recognize one another when they both came to work at the Lab back in Season 2, and still don't recall seeing one another there.
This is one of the only two episodes in which Mac does not wear his Detective Bureau pin. He wouldn't have had it in 2001, as it is only given to long-term detectives. In the (present-day) 2011 scenes, he wears a memorial US flag pin instead. (The other episode is 4.01, "Can You Hear Me Now?" where he is summoned to work straight from the airport and doesn't stop to change into his usual work attire.)
Creator's Favorite Episode: During the making-of extra in the Season 8 dvd set, Gary Sinise says that this is definitely one of his favorites, then adds, "probably my favorite episode" of the 160 or so they'd done at that point. He has since stated on social media that he and his family continue to watch it every September 11th.
