Deliberate mistake: After Mina leaves the car in Venice, Sawyer just manages to avoid several obstacles on the way, including a bend in the canal. But in the first scene, where Sawyer swerves the car around, its front should have slipped into the water anyway, considering the speed of the car and the tightness of the street, which makes a sharp L-turn at such close quarters next to impossible. But then the scene jump-cuts, and the car is well past the hazard.
Deliberate mistake: When the police officer is being ran over the tank you see him falling backwards. When it cuts we see his hat being ran over by the tank. However the way the officer was falling there is no way his hat could have landed under the tank's belt as it does in the next shot. (00:01:55)
Answer: After Quartermain is buried, we see a witch doctor performing magic above his grave and the clouds darken indicating something is about to take place. The witch doctor is chanting "Return" and the grave begins to shake. Although we do not see Quartermain come back to life it is most definitely hinted that he did and left room for a sequel which never came to pass.