Revealing mistake: When Dracula flies into the room to stop his brides from devouring Jonathan, the board carrying him is visible. (00:34:10)
Revealing mistake: When Jonathan closes the transactions in Dracula's castle, as Dracula's shadow is shown trying to strangle him, you can see Gary Oldman's real shadow on the right-hand side of the screen, standing in front of the shadow of Keanu Reeves. Also, in the final shot of the scene, as Dracula turns around and walks away, Dracula's shadow appears directly behind Jonathan, but Gary Oldman's own shadow can be seen on the right-hand side of the screen, moving in accord with the actor as he leaves the room. (00:17:26)
Revealing mistake: When Dracula looks up toward the door as he hears Jonathan and the others about to walk in on him and Mina, if you look at his left eye, you can see the edges of Gary Oldman's purple contact lens. (01:41:45)
Revealing mistake: When Dracula is standing on the bed, transformed into a giant bat, the red wound from Jonathan's gunshot can be seen on his chest before Jonathan actually shoots him. It is first seen as he says, "Look what your god has done to me", and more in the next two shots of his bat form, before Jonathan fires his gun. (01:42:30)
Revealing mistake: During Lucy's funeral scene, if you look at her abdomen as the camera pans through the shot, you can see Lucy breathing when she's supposed to be dead. Very obvious on a big screen, not as much on a small screen. (01:21:15)
Revealing mistake: When Mina and Dracula are at the restaurant, when Mina says, "Tell me, Prince... tell me of your home", they are sitting at a dinner table positioned very close to the wall with the frosted windowpanes, with hardly any room between the wall and the table. However, when Mina says, "With gowns flowing white", she is standing in front of the same window, and the chairs and the table are now sitting much further away from the wall, so that when Dracula walks away from the table to stand beside her a few shots later, he has to take several steps to reach her. (01:04:22 - 01:06:23)
Revealing mistake: After Van Helsing's lecture, there is a quick scene showing Jonathan as the prisoner of Dracula's brides. At the start of the scene, there is a close-up of one of the brides' eye, where you can see the edges of her contact lens. (00:56:57)
Revealing mistake: When Dracula escapes from Mina's bedchamber, he transforms into a figure of rats. If you look at the waist area beneath the humanoid rat figure's right arm, you can see one of the metal rods of the armature that was used to create the rat dummy. A couple of other rods are glimpsed as well. (01:43:05)
Revealing mistake: When Dracula enters Mina's bedroom in the form of green mist, at the end of the first shot, as the mist begins moving across the floor, a vertical beam of the green light that was used to color the mist appears beneath the chair that is sitting by the window (as stated in the film's official behind the scenes book, the effect with the mist was accomplished by using dry ice smoke which was lit green and superimposed on the set with a 50/50 mirror). (01:35:35)
Revealing mistake: When Jonathan is being seduced by Dracula's brides, right before their first bite, there is a close-up of one of the brides' eye, where you can see the edges of her purple contact lens. (00:33:45)
Revealing mistake: Dracula has no reflection, as seen when Jonathan is shaving, and when Dracula buys the newspaper in London. But when he assists Jonathan with the shaving, every time he dips the blade into the water bowl, his red robe can be seen reflected in the bowl. (00:26:40)
Revealing mistake: In the scene where Lucy is done in by Dracula in wolf form, as she dies, blood is exploded into the room by "supernatural" forces. If you look in the torrent of blood, you will see the gas, I assume carbon dioxide, from the special effect cannon appear and evaporate. (01:21:00)
Revealing mistake: In the close-up where Dracula first bites Lucy, the puncture wounds can be seen on her neck before he sinks his teeth into it. (00:40:35)
Revealing mistake: In one of the first scenes, Winona Ryder (as Vlad the Impaler's wife), is lying on the floor, dead. Gary Oldman's Vlad falls to his knees, heartbroken, right next to the "dead" Winona, who flinches. (00:03:34)
Revealing mistake: When Mina and Dracula are at the restaurant, as Dracula says, "The most beautiful place in all creation", there is an extreme close-up of his eye. If you look at the left side of the purple iris, you can see the edges of Gary Oldman's contact lens. After Mina describes Transylvania's beauty, there is another close-up of Dracula's eye (this time with a different color) and you can once again see the edges of the contact lens on the left side of the iris. (01:04:35 - 01:05:05)
Revealing mistake: When Jonathan is shaving, there is a close-up of the back of his head, where Keanu Reeves and his body double are unsynchronized: As Keanu's reflection shows him beginning to lower his hand with the razor, the hand of the body double standing in front of the mirror is still up by his neck, before the body double lowers the razor a split-second later. (00:26:20)
Revealing mistake: When Harker is in the train, the outside shot shows a blatant model train, with empty carriages, plus no people and no curtains, as opposed to the inside shots. (00:08:20)
Revealing mistake: When they are in the crypt to kill Lucy, they open the stone lid and look down. Clearly you can see glass on top of the inner coffin, yet later when Lucy goes in the coffin there is no glass. (01:24:55 - 01:27:05)
Revealing mistake: During the battle scene at the beginning of the film, you can tell that the group of soldiers in the background are just animatronics because their bodies remain stationary while their arms move in a clockwork repetitive manner. (00:01:45)
Answer: For protection from the inmates.
raywest ★