Continuity mistake: In the scene where Van Zan shows the dragon tooth to Quinn, Van has a cigar in his hand. But as he lowers his hand, the shot changes and the cigar vanishes.
Continuity mistake: I've seen it in other films but in this one it gets almost ridiculous. Van Zan's beard changes from pretty thick when he's introduced to almost shaved the same day after the first dragon fight then back to thick and fat a couple of days later while in London. Even if we believe he shaved after the dragon fight - which shouldn't be the case since the camera follows him almost the whole time - there's no way it got that fat 2 days later.