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)
Answer: Lucian does not die instantly after being shot by the silver nitrate bullet. This also is after he injects himself with Michael's blood. With that said there was a scene where Raze comes back with Amelia's blood (she is an elder). He checks on Lucian while dropping the bag of blood right mext to Lucian. I am absolutely certain he noticed this bag, injected himself with elder blood before he crawled out to stab craven in the leg. Lucian will be back and this was part of the story. When he comes back, they will show the audience in a flashback of Lucian injecting himself.