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.
This episode marks the only appearance of the Jem'Hadar and the Breen in Voyager, although they appear only as holograms. Three Jem'Hadar attack ships previously appeared (also in holographic form) in season 2's Parturition (1995). This is also the only appearance of the Breen outside of Star Trek: Deep Space Nine in the 90s and early 2000s Star Trek shows. The Breen make new appearances in the Lower Decks episode Trusted Sources (2022), and - most notably - Season 5 of Star Trek: Discovery (2017).
First appearance of the Hirogen since season 4, and the last in the overall series.
This episode originally aired as a feature-length episode but it was later broken up into two parts for reruns in syndication.