When he sees that Rambo is going to radio to his base, Lt Col Podovsky says "very good" in Russian. The way he pronounces it (ochen' khorosho) makes it clear that he doesn't know a single word in Russian.
While Co is walking through the jungle with Rambo, she continually has her finger on the trigger of her AK-47 (or AKM). This violates a basic firearm safety rule, known to every soldier and guerrilla, which states that the finger must stay off the trigger until the sights are on the target.
During the helicopter battle, the minigun appears mounted on the side of Rambo's chopper in a fixed forward position in some shots, is being aimed and fired by a POW in internal cut shots, and then returns to the fixed forward position in the exterior shots. Also, in some of the fixed forward position shots, the minigun appears to be either not rotating and/or to be a 3-barrelled M197 rather than the 6-barrelled M134 Minigun used in other shots.
When Rambo jumps off the chopper to rescue the POW's in the Vietnam People's Army (VPA) camp, he pulls off the mounted machine gun which has about 30 bullets hanging on the chain. However, he fires more than 30 bullets in the scene. Later when Rambo jumps off the chopper at the base, he pulls off the gun from its mount again with only 30 bullets left. When he fires at the technology though, he uses at least a hundred.
The weapon that Rambo holds in the helicopter is a single shot LAW rocket, which has a trigger on the top of the tube. This is followed by a short close up of his finger pulling the conventional trigger of a rocket propelled grenade (RPG). The LAW is back in the next shot.
The gunner in Rambo's helicopter shoots off one of the rocket pods on the enemy helicopter. In the next shot it is back on, and later comes off again just before Rambo destroys it with the rocket launcher.
In the final chase scene between Rambo's Huey and the Russian HIND Helocopter, you can see daylight passing through the missile pods on the Russian HIND, indicating that they are empty, but the helicopter fires them several times.
The helicopter drops the bomb causing Rambo to jump into the water. The helicopter is near the water and the Russian soldier is shooting in the water. He stops shooting and Rambo grabs him and gets in. Then while fighting on the helicopter, Rambo goes from wet to dry to wet again.
Although he does it seemingly instantly in the movie, it would have taken Rambo a long time to cover himself from head to toe with thick mud, then clean it all off immediately after he killed the soldier.
Rambo's helicopter makes a crash landing in the water. Colonel Podovsky closes in with his helicopter and is about to fire a missile. A closeup of Rambo's helicopter shows a hole in the windshield, but when it cuts to the wide camera shot, there is no hole in the windshield. It cuts back to the closeup, and there is a hole in the windshield, which Rambo fires a rocket launcher through.
When Podovsky reads the transcript of the intercepted radio transmission, it is totally different from the original radio transmission. Since he is reading it directly from a sheet, there should be no discrepancies.
When the riverine patrol boat fires at Rambo on the junk,in close up shots of the side of the turret guns, the belts are still as if they are not being fired. Yet in all other shots the belts are moving while the gun is being fired at full automatic.
From the time Rambo makes his break from the torture hut,until the end of the film--through much sloppy terrain and physical exertion--he continually shifts back and forth from filthy-and sweaty to clean-and-dry.
After Rambo shoots an arrow in a Vietnamese soldier's head, to save CO, the arrow changes positions with different shots. On the first shot it is pointing upwards and on a close-up scene it is pointing downwards.
About an hour into the movie, Rambo is struggling with the 'big' Russian guy in the back of the helicopter. After he manages to throw him out, he then takes control of the Russians' helicopter. Once he is seated in the pilot's seat, you get a front cameo shot of his face and in the background, you see another helicopter right on his tail (Rambo even turns around and takes a glance at the helicopter on his lead). Yet in the next panoramic shot of Rambo's helicopter skimming over the jungles of Vietnam, you see no helicopter.
After Rambo buries Co, the shot switches to a dolly of several Russian soldiers walking through the jungle. Through a break in the leaves, two crew members are visible walking in the river, one in a bright blue tank top and the second in black clothing.
The exploding mortar shell which goes off behind Rambo and the POW during the rice paddy ambush - both men would be killed in reality since the mortar shell has enough shrapnel to inflict third degree burns and blunt trauma.
During Rambo's insertion, he is aboard a converted executive jet with "low" wings and side-mounted jet engines. He jumps out of the side door in front of an engine. Actual parachute jumps are performed from aircraft with top-mounted wings from behind the engines to prevent jumper getting caught up in the wings and engines.
While on the pirate river boat, talking to boat's captain - he demonstrated RPG-7 as a protection from patrol boats. On the RPG-7 grenade, there are 3 lines in Russian with Cyrillic letters on the RPG-7 grenade which are translated into English like "Rifle Cartridges 7.62mm, model of 1943 year" (which, actually, are used for firing with AK-47).
Rambo fires the explosive arrowheads at two trucks on the bridge, yet in the next shot the center truck is seen burning as well. However, the center truck could have caught fire from the other two explosions.
This is after the helicopter drops the bomb causing Rambo to jump into the water. The helicopter is near the water and the Russian soldier is shooting in the water. He stops shooting and Rambo grabs him and gets on the helicopters landing gear. Rambo leans back against the helicopter and you can tell very easily that it is not Sylvester Stallone, but a stunt double.
Although the attack helicopter chasing is supposed to be a Mi-24 Hind-D attack helicopter, the SA 330 Puma used bears very little resemblance to an actual Hind-D. The most obvious difference is the lack of stacked gunner and pilot cockpits, found on all Hind-type helicopters
When Rambo lands the UH-1N Twin Huey/B-212 at the air force base you can see that they are using fire extinguishers to create the "smoke". In some scenes you can actually hear the fire extinguishers being "fired".
When Rambo is firing the supposed M60 into the equipment at the airforce base, the camera pans to the 7.62mm casings falling to the ground. If you look closely you can see that the casings have been modified to fire blank rounds. You will see what appears to be a small tube like object sticking out of the casings.
When the helicopter Rambo is flying heads back towards the POW camp, you can clearly see that the rocket pods are empty. The same is true when the other helicopter which pursues him appears, yet both choppers fire a number of rockets.
When the Russians are electrocuting Rambo, the lights around the compound flicker. Rambo throws the Russian guy onto the fence and then turns the electricity on full blast, and leaves it on. The lights around the compound do not flicker at all.
Near the end when Rambo is using a LAAWS rocket to blast the Soviet Hind Helicopter, pay close attention. A LAAWS is a simple tube, yet when Rambo fires it, he is clearly holding an RPG-7 launcher. Seems like they just reused footage from earlier, clipping it in quickly.
When Rambo boards the pirate boat and departs, the boat engine makes a "chug-chug" sound like a large single cylinder diesel engine. A closer look reveals two - 2 stroke outboard motors actually driving the boat.