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.
Factual error: When Rambo plays possum then suddenly takes out the Russian officer's Hind Helicopter he uses an M72A2 light anti-tank weapon (LAW). When fired, the M72A2 has a back blast that can kill out to 100 feet, which means he would have either blown up his own helicopter or killed all the MIA's he had rescued...
Character mistake: In the showdown scene between the Vietnamese officer and Rambo, the Vietnamese officer empties an entire magazine at Rambo from only about 20 metres away but only manages to hit the ground around Rambo's feet. What was he doing, aiming at his feet? He deserved to get blown up to bits for that effort.
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: 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.
Factual error: Near the beginning of the film, the airplane that will fly Rambo into the jungle is being refueled and prepared for takeoff. Ericson shines his flashlight into one of the jet exhaust ports to inspect it, an impossible task since the jet engines have already been started. Not even Rambo would be able to stand behind a jet exhaust without getting blown over or burnt to a crisp. (00:10:15)
Factual error: The Russian Hind helicopter is in fact a French-built Aerospatiale Super Puma with attached wings.
Other mistake: During a scene shot on the bridge, you see two vehicles pull up - later you see that another vehicle has arrived with reinforcements in an aerial shot. At this time, you see a man firing a automatic weapon, and then one of his fellow soldiers crossing directly into his line of fire, but the man is not hit.