At least four actors in the pilot (Jeremy Sisto, Connie Nielsen, Dallas Roberts, and James Chen) appeared in previous Dick Wolf shows. Jeremy Sisto played a detective on Law & Order (1990). Connie Nielsen appeared as a detective on Law & Order: Special Victims Unit (1999). Dallas Roberts played a criminal that crossed over Chicago P.D. (2014) and Law & Order: Special Victims Unit (1999). James Chen appeared as a CSU on Law & Order SVU.
Only episode to feature SAC Ellen Solberg (Connie Nielsen). Connie went on to star in a mini-series.