The antagonist here is played by Patrick Kerr, who frequently plays characters on other shows with a serious Star Trek obsession. In fact on the show Frasier (1993) its even stated his character has a restraining order from William Shatner.
At least one of the reasons Torres and Kim work on fitting holoprojectors around Voyager in this episode is that the production team of Star Trek: Voyager had, by this point in the series' run, become fed up with The Doctor almost always being confined to sickbay.
Persistence of vision is the phenomenon of the eye where an afterimage is thought to persist for a small fraction of a second on the retina. The belief in persistence of vision is based on the mistaken belief that human perception of motion is the result of persistence of vision. This myth probably stems from the idea that the human eye is just like a camera, when in fact there is much more to it then that. Misinterpretation of this phenomenon over several centuries has led to the persistence of this myth. One explanation may be iconic memory; but this is a subject of many arguments among different branches of the medical profession.
This is the third of three episodes that feature Janeway's Gothic holonovel, holosuite program Janeway Lambda one. The holonovel had originally been developed for "Eye of the Needle" but was not shown onscreen until "Cathexis".
This is the only episode of the series to address B'Elanna Torres' attraction to Chakotay. However, the issue is additionally raised in the novel Pathways by Jeri Taylor, the same person who wrote this episode.
The Botha alien uses a Kazon ship as one of his illusory vessels. The other illusory ship is not identified. However, the oft-reused studio model for the Talarian observation craft was used for the unidentified craft here and, this time, it was redressed with a purple glow from its nacelles.
One of three episodes during the show's first three seasons where Tom Paris remarks that an alien they've encountered on Voyager's viewscreen is either a friendly/pleasant fellow when really they're anything but; the Botha here and Jal Culluh in S1's State of Flux and Bharat in S3's Fair Trade.