This movie ties in with the movie Vampire Journals.
Anders Hove is the only actor to appear in all five films in the series, including the recently released Subspecies V: Bloodrise (2023). Hove did not appear, however, in the spin-off movie, Vampire Journals.
The Bloodstone in the movie was created via computer, as the original model went missing by the time filming had begun.
After it became clear that Kevin Spirtas and Melanie Shatner wouldn't be able to return for this sequel, director Ted Nicolaou originally considered doing a re-enactment of part 3's ending with Romanian actors who resembled Spirtas and Shatner, but it was instead decided to go ahead and use actual footage from 3 instead.
Although they appear at the close of the previous film, the Subspecies minions of Radu are not featured in this film. This is, thus far, the only film in the series where they do not make an appearance. With that, it is also the first entry in the Subspecies series that didn't involve David Allen with the special effects or make use of stop motion animation.