Beginning with Season 3, Fox decided to stop airing repeats of each week's episode on its cable outlet, F-X. The decision was made after several local Fox affiliates complained that the repeats were hurting their ratings.
This episode marks the first time that a place (Counter Terrorist Unit) gets a spot (freeze frame with the name written on the screen) during the "previously" instead of a person.
In a deleted scene for this episode, it is revealed that Season 3 takes place on a Wednesday-Thursday.
The President asks Dr Packard what she knows about "type 3 pneumonic viruses". She answers "Not a lot. They're fairly new." Aside from the fact that this imprecise virus name is fictional, no virus species is new. They have all evolved over a long time. Some strains may be new, due to mutation, but that is not what they were talking about.