The same panel where Tuvok accesses Sickbay's holomatrix in this episode also features in the previous one, Relativity (1999), as the location where the temporal disruptor was hidden.
Some of the footage of the planet, as seen from space, consists of stock optical shots that have been used in many past episodes of Star Trek: Voyager.
In the opening scene Neelix says to Paris, "Fool me once, shame on you. Fool me twice, shame on me." This line was previously spoken by Scotty in Friday's Child (1967).
47 References - When The Doctor tells B'Elanna and Harry to assist him, interface 047 is shown on the screen. When B'Elanna changes that display, other instances of 47 are shown on different lines of data.