Detective Lennie Briscoe was born on January 2, 1940.
Dana Elcar, who played Robert Cook, was blind in real life. He started losing his sight to glaucoma when he was playing Peter Thornton on the TV series MacGyver (1985). His condition was written into that series with Thornton also developing glaucoma.
This episode appears to be based on several separate cases/incidents:
- The 1983 Memorial Sloan Kettering Cancer Center hacking by the 414s.
- The 1962 Richard Angelo case. Angelo was an American serial killer who operated within Long Island and West Islip, New York. In 1989, he was convicted of murdering several of his patients and sentenced to 50 years to life in prison.
- The hacker group DoD (Department of Doom) seems to be based loosely on either the Legion of Doom (LoD) or the Masters of Deception (MoD), both very active groups in the late 1980s in the New York area.
John Dossett has played four different characters over the course of the series:
- Episode 3.19 Virus (1993) - Don Stuart.
- Episode 9.14 Sideshow (1999) - Frank Wellington.
- Episode 12.11 The Collar (2002) - Father Evans.
- Episode 16.3 Ghosts (2005) - Judge Martin Schnell.
Patricia Kilgarriff (Nurse Hillary Berg) also played the role of Pauline Best in Family Friend (2006) (episode 16.12).