Reid's cell phone number includes the digits 1414, which can be seen when JJ presses these digits on the conference phone.
The entrance to the D.C. subway was substituted with an entrance to the New York City subway. Several of the subway station shots, before the final climax in the subway, are also New York City subway stations, and the shots of the train flying by the camera are also New York City subway trains. The final scenes appear to be shot in the Washington, D.C. system, which is much newer and has different train cars.
When Rossi takes the anthrax medication, he says "Cent'anni! May you live 100 years!". "Cent'anni" is Italian for "a hundred years" and is a common toast at birthdays in Italy. Also, the complete sentence is used by ChefMD on his show.
In the episode "52 Pickup," Agent Todd gets in trouble for lying to a civilian. However, in this episode, Prentiss is told that lying is a part of their job.
Garcia: Hey, Reid.
Reid: Reid, wow. No, ah, no witty Garcia greeting for me?
Garcia: I can't be my sparkly self when you're where you are.
Morgan: I'm going to see you off to the hospital.
Reid: I'm about to get naked so they can scrub me down. Is that something you really want to see?
Reid: "Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it." Helen Keller
Reid: "It will become fine dust over all the land of Egypt, and will become boils breaking out with sores on man and beast through all the land of Egypt." Exodus 9:9