Factual error: When the Creeper eats the policeman's heart, there is nothing blocking the hole - the tissue above the heart should have collapsed downwards.
Continuity mistake: When the Creeper bumps their car at the early stages of the film, the boy turns his head to the left to see the back. Then suddenly the camera angle shifts and we see him turn his head to the right this time to see the back, which of course he couldn't have done that quickly.
Continuity mistake: After the cop's head is cut off, the cop car stops perpendicular to the road. When the girl approaches the car, it is nearly parallel to the road.
Other mistake: After the creeper cuts the cop's head off, how could the car both brake and steer?