Jennifer Van Dyck has played five different characters over the course of the series:
- Episode 1.21 Sonata for Solo Organ (1991) - Joanna Woodleigh.
- Episode 4.16 Big Bang (1994) - Shelly Conners.
- Episode 7.6 Double Blind (1996) - Jill Perry.
- Episode 16.19 Positive (2006) - Dr. Elaine Clemens.
- Episode 9.21 Ambitious (1999) - Morgana Palmer.
- Episode 12.14 Missing (2002) - Morgana Palmer.
Sekou Laidlow (Emerson Tyler) previously played the role of Prial in episode 14.11, Darwinian (2004).
Vondie Curtis-Hall plays a doctor in this episode but he also played a doctor in Chicago Hope (1994); Dr. Dennis Hancock.
This episode appears to be based on a 1997 report by Public Citizen about unethical AIDS research.