Continuity mistake: During the chase, when Rambo escapes from jail, the police car jumps and the back hub-cap flies off. The next time you see the the police car all the hub caps are on. And when the police car goes through all the mud in the field, the back end of the car is all muddy, but a few seconds later it is all clean again.
Continuity mistake: The sheriff left his hat in his upside down car. He suddenly has it at the gorge.
Continuity mistake: During the motorcycle chase, just after the police car breaks through the wooden gate, in the close up of Rambo's motorbike its wheels go through two puddles, a short space of land, then another puddle. Keep watching closely as he rides through the mud. In the overhead shot of Rambo approaching the road at an intersection, he goes through the same three puddles again (the third one is hidden behind a tree, but you can still see the splash).