When Blade, Whistler and Scud confront the head Vampire, an earlier shot of Whistler talking, but with the audio removed, is used as a reaction shot, leaving Whistler to appear to foolishly mouth a line he has just said.
When Whistler looks through his infrared sniper scope as Blade and the pack walk into the first club only blade shows up with a heat signature, the full vampires show up as blue/green meaning no heat. Later in the sewer, Whistler looks through infrared goggles and now the vampires show off as red meaning they are giving off heat.
After the fight scene between Blade, Asad, and Nyssa, where Blade tells the 2 of them to remove their masks, Nyssa begins to remove her mask with her left hand and then in the next shot we see it has become her right hand.
When Rush is charging at Blade on the motorcycle he dodges Blade's weapon and Blade is crouching at the end of the alley. In the next shot Blade is standing and spins into a crouching position to catch his weapon.
In the final scene, they enter the skyscraper's helipad through glass doors. The shot behind them shows they are high elevation and there are no trees. But, when the camera is pointed back to the doors you can clearly see the reflection of at least two trees in the left glass.
Lighthammer was bitten and for hours does not turn, yet when Priest is bitten within 20 minutes, he turns. This may indicate that the spread of the Reapers' mutated virus depends on some set of variables that may include: amount and/or location of transmission, recent feeding of the infected host, general health/resistance of the infected host, number of generations between Novak and the carrier, et cetera.
After Whistler gets rescued he and Blade talk about how long he's been out. Blade doesn't tell him but Whistler surmises he's been gone for years. After this scene he sees Scud and says "I've been gone for 2 years." Whistler could not know exactly how long he'd been gone.
Nyssa is a "pure blood" (born a vampire) but she has a scar above her lip and fillings in her teeth. According to the logic of the movie, a pure blood vampire would never scar and, we might infer, would never need dental treatment.
During the final battle where Whistler throws Blade his sunglasses, Whistler's actions in the background are inconsistent, revealing that it was not a straight throw-and-catch and that some editing trickery was used.
In the opening scene when Blade is chasing the vampires outside, Blade cuts off Rush's helmet using the bike tire, but where he is going to cut it there is already a pre-made crease in the helmet which splits perfectly without any effort.
When Chupa is firing his machine gun at a fleeing Reaper in the vampire nightclub he shoots two ordinary vampires, one of whom is wearing a distinctive red outfit. Then in the next shot, the Reaper has moved along the wall a little way and Chupa is still firing at it he kills the same two ordinary vampires again. The distinctive outfits make it obvious.
When in the House of Pain chasing Nomak, Blade tells Nyssa to wait here (in the hallway) since it's dawn outside as seen through the planks on the windows, yet it shows Scud at the same time in the plot trying to get the God lights to work on the truck since it's dark as night outside.
When Whistler throws the sunglasses to Blade towards the end of the film, in the near shot of Blade catching the sunglasses, Whistler can clearly be seen in the background "throwing" the sunglasses again well after they are caught.