Visible crew/equipment: When Blade takes Karen to the hideout, Whistler injects her and tells Blade, "I give her 50/50 if she makes it through the night." In the shot where he says this, look directly behind Blade (near the ground, next to the drawers), and you can see a piece of equipment (it looks like extra lighting, but it's hard to tell) being moved out of shot by an out-of-sight crew member. (00:18:29)
Audio problem: When Frost first enters the conference room with the rest of the members of the house, the older member with the symbol tattooed on his forehead scolds Frost about how he's not a pureblood. In a shot down the table (probably only noticeable in widescreen), you can see the guy on the right side of the screen, but his mouth isn't moving, even though you hear him talking.
Revealing mistake: When Traci Lords approaches Blade, he tries to shoot her with the shotgun only for it to click, empty. He then proceeds to impale her with the silver stakes mounted in the end of his gun. If you look closely (probably more noticeable in full screen), you can still see the tips on the end of his stakes when she hisses at him, meaning that they're not actually inside her, even though she disintegrates in the next shot as if they were.
Chosen answer: It would seem Deacon has gathered a lot of strength around himself, in followers of "young" vampires like himself. After he kills Gitano he just abducts all the vampire elders, showing his followers are a lot stronger than the elders are. So they probably couldn't have killed him even if they wanted to, not unless they want to unleash a war. They thought his pursuit of the vampire god was totally pointless, so they let him waste his time and were probably trying to find a way to get rid of him.
lionhead