The holographic generator used by Iden and the other escaped holograms is a re-use of the artificial intelligence prop from the episode Think Tank (1999).
Voyager launched in 2371, while the Jem'Hadar were first encountered by the Federation in 2370, which explains how the species can be included in Voyager's holographic database. By this time Voyager was also receiving tactical updates from Starfleet via the MIDAS array.
When confronted with working on a repair task instead of a medical task, The Doctor remarks, "I'm a doctor, not an engineer." This references the line ("I'm a doctor, not a...") commonly uttered by Dr. McCoy in Star Trek (1966).
This episode marks the only appearance of the Jem'Hadar and the Breen in Voyager, although they appear only as holograms. It is also the only appearance of the Breen outside of Star Trek: Deep Space Nine. Three Jem'Hadar attack ships previously appeared (also in holographic form) in season 2's Parturition (1995).
This episode originally aired as a feature-length episode but it was later broken up into two parts for reruns in syndication.