Continuity mistake: During the fight scene towards the end, Michael Corvin (now half lichen/half vampire) flies through the air from being hit. At this point Michael’s color is a translucent black/grey. As he flies through the air you can see that his feet are white.
Continuity mistake: At the shooting range, Selene is shown firing a black USP without a compensator. It then cuts to an over the shoulder shot, and she is now firing a two-tone USP Match (which she supposedly receives from Kahn to test out a few seconds later). It then cuts to a frontal shot of her, and she is once again using the same black USP. She never stopped firing, so she couldn't have switched guns.
Revealing mistake: After Selene jumps off the building at the beginning and lands, there is a very large upwards pull (that stays in place until the camera cuts away) in her cape near her head that is in fact the drop wire running under her cape to the harness on her back (although the wire has been edited out).
Continuity mistake: Selene is in Michael's apartment looking through photos, you can see the door to the apartment fully open in the background. When the phone rings, and we see Michael walking towards his apartment, the door is only partially open.
Continuity mistake: When Selene runs up the stairs to release Michael from the chains, the door she left wide open is almost closed when the pursuers reach it.
Continuity mistake: In the first scene when Rigel is crouching, taking pictures of the werewolves, he is holding the camera in his right hand just as he is about to jump down. However, when he is jumping, the camera angle changes and it can be seen that he is no longer holding a camera in his right hand.
Other mistake: When Selene's car plunges into the Danube, her car hit the bottom of the river on it's side (the passenger's side). When the camera closes up to the window of the car, you can see water flowing in from the roof of the car (as a result from the holes created by Lucian). It should flow (or at least accumulate) towards Michael's direction because of gravity but it did not.
Continuity mistake: When Michael was captured and hung up, and meets Lucian face to face, Lucian injects blood into him and the syringe has an air bubble in it. In the next shot, the bubble has gone and the syringe is entirely filled with blood when being injected into Michael.
Continuity mistake: During the fight scene between the two Lycans, it shows a shot of Taylor (short Lycan) receiving a cut across the left side of his chest, but when it shows him in his human form it is on his right.
Continuity mistake: In the last fighting scene between Victor and Michael, Victor's face gets scratched and it starts bleeding. In the next shot, his face is completely cleared of his scratches. And in the next, the scratches appear again.
Revealing mistake: At the end of the film when Viktor and Michael are fighting you can see Viktor pulling his punches.
Revealing mistake: The edges of Selene's bright blue contact lenses are VERY visible in the scene near the end where she is on the ground, talking to Viktor.
Factual error: Selene's guns are apparently capable of firing 30 rounds without reloading. Considering the size of the ammunition, this is physically impossible.