The scenes in the vampire nightclub were filmed in the Dublin tourist attraction "Bram Stoker's Castle Dracula", which has since closed.
This is not the first time Anthony Head has acted as a mentor teaching people to fight vampires. One of his most famous roles was as Rupert Giles, Buffy's "Watcher," in Buffy the Vampire Slayer (1997).
In a 2022 interview with Behind the Lens Online, Conor McMahon explained how the process of casting a short promo for the film led to a major change in the initial script: "In the casting of that, I found my vampire actor, but I couldn't find anyone to play off him. Like I was casting all these other mid-20s actors because I was looking for a best friend, and, just by chance, some wires got crossed and this young guy, Karl Rice, who was like 15 or 14 at the time, came in to read and I was like, 'Oh well, he's the wrong age, but I don't want to send him away' and I just brought him in. And it was just, in the minute I saw the two of them acting together, there was something about a younger teenager saying the lines and talking about vampires... There was suddenly this other layer to it. Then the idea came to me when I saw the two of them, 'Oh my God they have to be brothers' because if the stakes were high before, you know if you're gonna stake a friend, but what about a family member? That's a much harder dilemma... So I went home after that casting and I rewrote the whole script."