Continuity mistake: When Selene breaks the glass and takes out the old book the amount of broken glass on the book differ between shots. (00:39:55)
Revealing mistake: In the fight scene between Michael and Viktor, Viktor throws Michael in to a column and Michael lands face down. You can see his wire harness bulging under his pants. (01:47:15)
Continuity mistake: When Lucian goes flying over Selene's car, in the overhead shot we see that the road below him has large parts with visible concrete because there are no paving stones. But in the next shot, a close-up of Lucian landing on his feet, the road is fully paved with paving stones. (00:28:20)
Continuity mistake: As Viktor's tomb is opening there is a shot from above showing Selene looking down the opening tomb. Watch the placement of her feet. In the next shot, her feet have moved closer to the opening. (00:44:40)
Continuity mistake: When Erika discovers that Michael has been bitten - just before he leaps out of the window and escapes the vampires' mansion - there is a patch of blood above Michael's eye that disappears. (00:36:55)
Chosen answer: In most of the shots, Lucien takes his coat off when he changes to wolf form, and the blade would be attatched to a mechanism in him coat. Also, the film gives us an example of the blade hurting a vampire: bloodloss. And that kind of weapon could do some serious damage, and as it probably wouldn't kill the vampires, it would almost definitely slow them down.