Though he doesn't appear physically in this episode and remained uncredited, Jeff Goldblum had a vocal role as the New York City radio announcer.
In the book, Randall Flagg is described as having been involved in political activism of various types. He is of indeterminate racial origin, looking like a swarthy man so he has been involved in both the KKK and white supremacism, and black radicalism. In the miniseries he has blue eyes and is clearly Caucasian. He wears a badge saying "How's your Pork?" (a reference to the police). His face is also hidden most of the time, unlike in the miniseries.
Stu Redman (Gary Sinise) is shown in the Vermont Disease Control Center to be reading the 1991 novel "Maximum Bob" by Elmore Leonard. Stephen King references Leonard in some of his other fiction, such as his 2011 novel "11/22/63".
Circa 51 minutes in, "Sharp Dressed Man" by ZZ Top is playing, but it's slowed down to 118 BPM. The original is 127 BPM.
Ray McKinnon and Ed Harris would also star together in the Stephen King film Needful Things, as well as Apollo 13.