During the climax Colleen gets into a cab by herself to pursue David and one shot shows hands resting momentarily on the back of her seat.
As the Hulk destroys the roll up prop garage door at the gas station, the real garage door can be seen rolled up in place, to make room for the prop door.
After the Hulk, played by Lou Ferrigno, checks on the woman with the newborn baby, he hears sirens and starts to run away from the gas station. As he's running, it's quite clear that Ferrigno is not wearing the Hulk contact lenses.
Towards the end when Colleen is chasing after David she is stopped at a level crossing. Looking out the right hand side window there is a freight train going through, looking through the left side it is a passenger (amtrak) train heading in the same direction.
At 45:18, a crew member can be seen inside the hut.