Continuity mistake: During the crypt scene, when Lucy's body is interred, the shots of her in the glass coffin and later rising out of it, show dramatic difference in the depth of the coffin. (01:24:55 - 01:27:05)
Continuity mistake: When Van Helsing breaks the news to Quincey after reading the "Vampyr" book, as he says, "Yes, we may still save her precious soul", he's gripping Quincey's coat, and Quincey's left arm is down, but in the previous shot, Van Helsing's arms were down by his side, and Quincey was holding onto the hat on his head. His other arm changes position as well. (01:14:15)Kylantha
Visible crew/equipment: 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)David8366
Factual error: At the beginning of the movie, it was stated that Constantinople was captured by the Turks in 1462. The Turks actually captured it in 1453.