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: 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...
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.
Revealing mistake: In a scene towards the end, we see a crowd of Vietnamese on a riverbank firing their machine guns into the trees...one soldier clearly walks directly in front of another soldier who continues firing away without hitting him.
Continuity mistake: As the Russian Hind comes up over the trees, it angles just right and it can be seen that the rocket launchers are empty.
Continuity mistake: When the Russian chopper first spots the Huey on the ground, smoke is pouring out the left side of the Huey. A second later, there's barely any smoke.
Continuity mistake: In the aerial pursuit, the Huey goes from in front of the Hind, to port, then back to the front in a matter of five seconds.
Factual error: In the shot where Rambo is blowing up everything in sight from the Huey, there's a quick moment when it is seen from the front. The chopper has two seven tube rocket launchers, and after he fires all the rockets, there are trailing wires on the starboard pod. This is wrong because these launchers, as well as the nineteen tube model, fire 7.65 inch rockets that are electrically primed and fired from a contact pin in the rear, so no external wiring exists. Also, after he fires all the rockets, and therefore has no more, in the next shot, the launchers are loaded again.
Factual error: The Russian Hind helicopter is in fact a French-built Aerospatiale Super Puma with attached wings.
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.