Continuity mistake: When Frost has the head pure-blood vampire on the beach, after he pulls out his first vampire tooth you see blood all over his mouth, but when it shows the closeup of him pulling out the other tooth, there is no blood.
Continuity mistake: When Blade gets his serum, Whistler holds his hand, then they see the girl run. In one shot, Whistler goes right, leaving the suffering Blade. In the next shot (close up on Blade), you can see that Whistler is still holding Blade's hand.
Continuity mistake: In the big fight scene in the end between Blade and Frost, the blood smear on Frost's face changes sides a few times.
Continuity mistake: The bloody makeup on Whistler's face and neck changes constantly throughout the scene when he gives his last words.
Continuity mistake: When Blade is leaving the shop towards the end he fills up 6 phials of EDHD, but he uses 9 phials total. 2 On the 2 people in the hall when he first gets to the building and then 7 more on Deacon at the end.
Visible crew/equipment: Near the start when the vampire that's been burnt gets taken into hospital, watch the big glass cabinet as he gets wheeled in by 2 doctors - the crew and the boom mic are reflected in the glass.
Continuity mistake: In the House of Erebus, right before Blade jumps off the ledge to fight Frost, you see that Karen is standing on the ledge above everything and Mercury is standing down below on the platform. But when Karen's shooting at her, Mercury is coming down the stairs from above.
Continuity mistake: In the shot where Blade knocks the serum down from the wall, he throws one at Frost, then throws five more at him and finally throws the last one in his head. That's seven shots of serum, but when he catches it behind his back there are only six in the pack.
Revealing mistake: When Blade uses his booby-trapped sword to knock down the serum from the wall at the end of the movie, you can tell the zoom in of the shot was sped up, as the rotating-timer-thing is spinning quicker than normal, and the screen is vibrating quickly.
Visible crew/equipment: In the shot where Blade and Karen are running across the rooftop from the police firing at them from the hospital/morgue window, you can see the arms of a man holding a paintball gun on the right side of the screen. Paintball guns were used to fire projectiles that mimic the spark and smoke effects of bullet strikes.
Continuity mistake: When Blade gets captured and stabbed in the room where the "Vampire Bible" is, he is not wearing an ear piece. In the next shot, he is.
Continuity mistake: When Blade gets back from the park after meeting with Frost and getting serum, he discovers Frost's men have been there, and sees Whistler. When Blade moves the tape, which is in a metal rotating stand, the stand rotates on its swivel, but in another shot it has only moved a little bit and hasn't rotated either. The tape would've been facing the other direction because the stand swivelled, but instead it remains in the same position.
Plot hole: in the room which contains manuscripts from the book of Erebus, Blade senses the child vampire but when he actually comes face to face with her, he offers her his hand as if she is human. This is only a mistake because she moved like a vampire and he showed earlier on the film that he was very capable of sensing whether people were vampires or human. Yet he didn't notice that she was.
Continuity mistake: During the final battle, right after Frost's arm regenerates and he says "It's too late, Blade!", Blade begins swiping his sword at Frost rapidly. You can hear the sound of Blade's sword slicing into Frost's shirt, and even see numerous pieces of fabric from the shirt flying about in the air as Blade shreds off pieces. Yet, for the rest of the scene, Frost's shirt is almost completely undamaged, save for one or two small tears. This makes no sense, as we had just seen and heard Blade slicing off numerous pieces of fabric from the shirt. The pieces seen flying through the air were actually added later using computer effects to make the scene look more dramatic, thus creating the continuity problem.
Continuity mistake: When Blade drops Karen off, she walks to her apartment and as she approaches the elevator a blonde woman walks up to its doors and stops, but in the following shot the blonde woman is now just coming into view and then stands behind the black woman instead of at the elevator doors.
Revealing mistake: When Blade is fighting Frost's men near the end, Blade kicks an Asian man to the ground. When he hits the ground, you see he hits some sort of mat or pillow under the dirt.
Continuity mistake: When Karen turns on the UV lamp the first time and starts to burn Pearl (the enormous record-keeper), watch closely. In the first shot from the front, Pearl has no burns yet and the air is clear. It immediately cuts to an over-the-shoulder shot and not only does Pearl's arm instantly have burns on it (that had no time to appear between cuts), but there's also smoke in the air that wasn't there in the previous shot. (And also had no time to appear between cuts).
Audio problem: Right before Blade throws his sword to retrieve his EDTA in the final battle, he leaps to his feet as Frost attempts to stomp downwards on him. As Frost's foot his the concrete ground (or Blade's shoe, as it's unclear from the shot as the impact is out-of-frame), the audio features an incredibly loud and out-of-place flesh-on-flesh punching sound effect, instead of a proper "shoe stomping concrete floor/Blade's boot" sound that should have been played.
Continuity mistake: When Whistler is giving Blade the injection, watch the vial. It starts full, then in a close up, you can see the serum level drop. Then the camera goes to a wide shot, and the fluid level is almost full and dropping, The next close up, and the serum level falls to completely empty.
Continuity mistake: In the subway, Blade and Quinn are fighting on the edge of a subway station for at LEAST two straight minutes as a train barrels by. In NYC, it takes a subway car one to two seconds to pass a stationary point when moving at normal speed. Even being generous and saying two seconds per car, what subway train has sixty cars in it? (normal is eight, I believe).
Continuity mistake: Frost says near the end of the film that the spirits of the twelve will awaken the Blood God. Fair enough, but when the prophecy is first translated, you hear twenty beeps as pictures of people pop up around the circle, implying that there are twenty people standing around it.
Continuity mistake: In the beginning of the movie when Frost leaves the meeting, as he leaves the sound from his shoes is delayed.
Other mistake: Right before Blade confronts Frost at the end, he is shown beating up several henchmen vampires using punches and kicks, before grabbing his sword. As he grabs his sword, you see several of the henchmen vampires "burning up" in the background. However, it was earlier established that to "burn up", vampires had to be killed by traditional means. (Staked with silver, exposed to sunlight, etc.) So it makes no sense for these henchmen to burn up from only being punched/kicked. It can't be due to his sword, as he twirls it in front of them, and only after they are already burning up.