Continuity mistake: Just before the giant tarantula attacks the house where heroine Mara Corday is studying, you can see several book on the library table at the big picture window. The largest book on the table keeps shifting positions in several scenes.
Factual error: When they are driving in the convertible, before the tarantula attacks them with the stones, if you look at their hair, it's not moving with the wind. If they were driving a convertible that fast in real life, it would.