Revealing mistake: When Jimmy and War are fighting over the gun near the end of the movie, you can see that many shots are reversed, as the fire behind them is not burning upwards like regular fire, but appears to be "sucking" downwards, back into the barrels.
Revealing mistake: When Jimmy hands the priest the crow, in the closeup it is really the bird, moving around and squawking, but in wide shots, it is a very stiff and motionless doll.
Revealing mistake: When Death/Satan is killed at the end, you can see the rocks that he is impaled on move with his own body movements, much like prosthetics attached to him.
Revealing mistake: In the beginning, when the miners and Indians are fighting, you can tell they are all pulling punches and trying not to really hurt each other. Some of them even visibly miss punches and kicks by large distances.
Revealing mistake: When Jimmy attempts to kill himself, the bullet hole on his back is far above where he shot himself in the chest. At least 4-6 inches higher, AND the gun was slanted downward.
Revealing mistake: When War and Jimmy are fighting, you can see a brief shot of a window exploding. This same shot is shown again (but longer) later on when War explodes.
Revealing mistake: War manages to pick up his gun out of a barrel of burning materials, without getting physically or even visibly effected. The gun does not even have any sign of being in the fire, no smoke, no burn marks or anything.
Revealing mistake: When "War" explodes close to the end of the movie, you see a window being blown apart, but you can see there is nothing behind it and that is was just an on set window blowing up, and wasn't caused by the explosion outside.
Revealing mistake: When Jimmy and War are fighting outside the church, the gun they have shoots bullets, which fly into the church. The only problem is that there is almost no shot where the gun is pointed towards the church, so it makes no sense there are bullets constantly whizzing around inside.
Revealing mistake: When the hearse driver slams the brakes, in the next shot, it is obvious the car was already stopped and just shaken from off camera to make it look as though it stopped. No car can brake that fast.
Revealing mistake: When Lola is cutting out Lily's eyes, you can tell from her movements that she is not really cutting them out.
Revealing mistake: The bug-zapper that is supposedly electrocuting Pestilence doesn't actually touch him.
Revealing mistake: When Luc and Jimmy fly about at the end, in some shots you can easily tell it is stunt doubles and not the actors.
Revealing mistake: When Luc cuts out Jimmy's heart, you can tell it is not really beating and that Luc is just manipulating the prop with his fingers to make it look so.
Revealing mistake: When Jimmy and War are fighting over the gun outside the church, a series of shots is fired, and you see impacts of the bullets inside of the church, yet there are no bullet holes in the walls or doors. The only sign is a single window which blows up, but there is no way all the bullets could have gone through that window.
Revealing mistake: In the wideshot of Death/Satan impaled on the rocks at the end, you can tell the image onscreen is using a split-screen effect, as both sides of the picture wobble slightly in different directions, independent of each other.
Revealing mistake: After War blows up, not all of the movement of the smoke in the church matches. Some of it is flowing the wrong direction, even though it all came from the same area.
Revealing mistake: When Luc stabs Jimmy and removes his heart, you can easily tell from the distance between Luc's arm and Jimmy's torso that he stopped the knife before it got close to Jimmy.
Revealing mistake: The body of the virgin sacrifice (The black guy) moves when they set Jimmy down after taking him off the cross. His hands move up slightly. And it is not the camera movement.
Revealing mistake: When Luc pushes Lola into the totem pole at the end, as they begin to have sex, the totem pole, supposedly heavy, sturdy wood, shakes pretty heavily when Lola hits it.
Answer: As I understand it, it all had to do with a spat between the director of the original Crow movie (Alex Proyas, who had "approval" of all the subsequent Crow movies) the producer of the Crow movie franchise, Jeff Most, and Miramax. Miramax eventually caved in favor of the producer and it was made into a "non-Crow entity" when Miramax reportedly signed Eminem to play the bad guy.