Continuity mistake: When Rambo fires the rocket launcher at the Russian Hind helicopter, he is clearly seen aiming a LAW rocket launcher. The LAW is fired by pressing a lever on the top. But when Rambo fires, a quick edit from a previous shot (on the patrol boat) shows him pulling a trigger from the Russian RPG launcher he used to dispatch the Vietnamese patrolboat earlier in the film. The film returns to show him holding the LAW rocket launcher again.
Continuity mistake: When Rambo has rescued his first POW and running to escape to meet his check point, he is followed by the Vietnamese soldiers who chase him knee deep through a muddy swamp. The film scene then shows Rambo, seconds later, still running with the POW, but then returns to the Vietnamese soldiers who now have wet but very clean trousers.
Continuity mistake: In the end of the film after Rambo blows up the Russian helicopter, there is a hole in the front window through which Rambo shoots the rocket. In the next few scenes we see Rambo's helicopter and the hole in the window is gone, then it's back again, then it's gone, then it's back again when he lands.
Continuity mistake: In the POW camp, Co Bao is discovered by a guard who points a handgun at her. Rambo shoots an arrow into the guard's forehead, who then falls back against a tree with his cap down low over his eyes. In the next shot his cap is much higher on his head, and the arrow is pointing at a different angle. How could his cap have moved up that far with the arrow holding it to his forehead? For that matter, how could the arrow have moved when it was firmly embedded in the guard's skull?