The film takes place in 2015.
Although the film includes flashback footage of Bill Nighy, this is the first Underworld film not to feature new performances by Nighy, Michael Sheen, or Brian Steele.
In the original script, which was written in early 2011, Selene's Death Dealer outfit is not in the same room where she is after she wakes up, and instead she wears a thin medical gown, similar to the one that main character Alice wears in Resident Evil: Apocalypse (2004) until she finds a similar outfit in the vampire coven hideout and changes into it after the gown starts falling apart from filth and blood following the previous action sequences.
The language Thomas and David speak with each other when David bring Eve into the coven is Russian.
The film's release date is on the same day as Underworld: Evolution (2006)'s, released six years earlier.