Errors in geography: A small American flag is visible on the "Russian" helicopter that Rambo steals.
Continuity: While kick-boxing in Thailand, Rambo offers his right hand to his opponent who fell on ground but when he comes up he's holding Rambo's left hand.
Factual errors: When the troopers lead by the Colonel stops no sound is heard, all of a sudden you hear the sound of a helicopters rotor fade in, a few seconds later the helicopter appears and starts to slaughter the men. The night was clear and it was in a desert, those are ideal conditions for sound to travel (even a whisper will be heard over a good distance) and seeing how a helicopter creates a very high sound from both the motor and the rotorblades they would have heard the helicopter several minutes in advance.
Factual errors: Almost every time the Russian gunship helicopter attacks and is filmed from the front, there are muzzle flashes coming out of the rocket pods, but no rockets are being fired. Even if rockets were being fired, there would still be no muzzle flashes.
Factual errors: Zaysen’s rank is a Colonel, but he wears a kind of mixture between Senior Lieutenant (3 small stars and 1 stripe) and Colonel (3 big stars and 2 stripes -- he has 3 small stars and 2 stripes). His army coat is also obsolete.
Factual errors: Soviet soldiers can be seen wearing different kind of hats (winter and summer ones) at the same time, which can't happen in the real Army.