When Vanessa shoots Bob, after he escapes from the vehicle, the first bullet misses (hits the ground). Then two shots hit him, but if you notice the right side of his blazer, a third shot hits him but there's no sound.
When Vanessa is attacking Bob in the caravan, she knocks a plant and some other items down, then she strangles Bob. However when the detective goes to look at Bob's body, the plant has vanished from the floor, and the mess made around Bob is different.
When Bob and Vanessa are fighting in the trailer Bob fires off 19 shots. Bob appears to be wielding a .45 semi-automatic pistol with a standard magazine, which means it could hold 9 bullets (8 in the magazine and 1 in the chamber). Even an extended magazine (which would have been clearly visible protruding from the bottom of the gun handle) would only hold 14 bullets maximum.
When the girls are sitting in the plastic chairs watching the TV in the jail hall, in one shot Mesquita bends down and leans against the only empty plastic chair. Then in the following shot she's not there.
When Rhonda and Vanessa chat while they sit on the jail beds, Rhonda's arms/hands keep changing position between back and front shots. They alternate from resting in her lap to fiddling with her hair to having her head resting on her hands, etc.
When Vanessa is prostituting, she gets picked up by a man. They drive into an alley and the alley is bathed in bright sunlight. When they get out of the car however, the alley has no sunlight shining on it.
It is said that Vanessa is diagnosed with Antisocial Personality Disorder, but in the Diagnostic and Statistical Manual of Mental Disorders, this diagnosis cannot be given to anyone under 18 years of age. Instead, a juvenile is diagnosed with Conduct Disorder.