This story contains the first mention of Kes and Neelix's break-up, which happened offscreen at some point during the past few episodes. In Warlord (1996), Kes had expressed annoyance with Neelix and ultimately asked for the two of them to spend some time apart, but this was revealed to be the work of a malevolent alien whose consciousness was occupying her body and not Kes herself.
Since Voyager is shown traveling through normal space again, the crew's journey through the Nekrit Expanse must have come to an end sometime prior to this episode.
T'Pau, an important Vulcan figure who appeared in Star Trek: Enterprise (2001) and Amok Time (1967), is mentioned as being one of The Doctor's added subroutines.
This episode gives us the first confirmation that holodeck characters are indeed hollow, possessing no internal structure.
This episode marks the first appearance of Kes' navy blue one piece uniform.