The little girl that plays young Selene is Lily Mo Sheen, the daughter of Kate Beckinsale and Michael Sheen.
While filming a scene where Selene and Michael look at each other longingly, director Len Wiseman surprised the cast and crew by playing Bryan Adams' song "Everything I Do (I Do It For You)", at which everyone started laughing.
According to Tony Curran, he stipulated in his contract that he wanted to be able to keep his vampire fangs in at all times, even when he wasn't filming.
Zita Görög (Amelia) had to have her lines dubbed over because the microphones didn't pick up her voice.
The opening battle was filmed on a set built on a ski range, with the hope of heavy snowfall. In the end, snow only came in hours before filming was supposed to start. The snowing seen onscreen is completely natural and not man-made.