For advertising the show, stock images were purchased from various stock image agencies to create a variety of people to show as part of the 4400 missing people. This was most likely to avoid paying various actors to use their image for the advertisement purpose.
Joel Gretsch (Tom Baldwin), Jacqueline McKenzie (Diana Skouris) and Patrick John Flueger (Shawn Farrell) are the only actors to appear in all 44 episodes of the series.
The address of The 4400 Center, 6265 Crescent Road, is the same as The Chan Centre for the Performing Arts, University of British Columbia, Vancouver. The Chan Centre was the filming location for the exteriors and some interiors (including the main lobby) of The 4400 Center.
Seacrest Senior High School in this series is also the location of Smallville High in Smallville (2001}.
The lake at which the 4400 return is the same lake used in an episode of the first season of Los expedientes secretos X (1993).