Plot hole: Alain joins the Legion, goes through extensive training and eventually gets his photograph taken. That's how Galgani recognises him and sends two men to kill him. They arrive with a platoon at the fort just after Alain, Mackintosh and Luther. The photograph would have taken a while to get back to France and then the two men would have to go through the same training. So how do they both end up in the same fortress after they joined the legion long after Alain?
Continuity mistake: During the ambush at the waterhole, the Arabs steal the Legionnaires' supplies by leading away the donkeys upon which the supplies were mounted. Why didn't the Legionnaires shoot the donkeys? Without them to carry the supplies the Arabs wouldn't have been able to take all before they withdrew.
Continuity mistake: When Alain and the big German Legionnaire are fighting in the barracks, the German throws him down upon a wooden table, smashing it and the nearby bench to pieces. The very next shot shows the German grabbing up the magically restored bench with both hands as he prepares to slam it down on Alain's head.
Plot hole: Normally, one's first reaction upon grabbing hold of a smoking explosive satchel would be to fling it away quickly, correct? Why oh why then did the Legionnaire officer grab it and run away with it in his hand, causing it to blow him (and all the ammunition) to bits moments later? A pretty senseless act for an experienced commander, if you ask me.
Continuity mistake: During the first Arab attack on the Legionnaires camping around the waterhole, watch Alain (Van Damme) carefully. One scene shows him firing and reloading, firing and reloading at some Arab swordsmen rushing down a slope at him. During one shot he fires his rifle slightly DOWNWARD not upward, and yet the target Arab falls dead.
Revealing mistake: When Alain is holding Guido's dead body and telling Steinkampf that he "died as a Legionnaire", you can see Guido swallow if you look at his throat.
Plot hole: When the Arab horsemen swarm into the Legionnaire fortress during the final assault at the end of the movie, the Legionnaires all crowd at the smoke-filled gate entrance and fire blindly into the haze, hoping to hit something. That's dumb! Couldn't they have pulled back and lain in wait, picking off the Arabs one by one as they rode through the gateway? It's basic military tactics!
Continuity mistake: At the end of the film when the mortally wounded Macintosh shoots Galgani's henchman dead, he draws back the bolt of his rifle, ejecting the spent shell. A minute later when Alain (Van Damme) throws him a bullet to kill himself with, his rifle bolt is magically down in place again; he has to draw it back a second time to place the bullet in.
Continuity mistake: During the penultimate Arab assault on the Legionnaire fortress, some Arab horsemen are lobbing satchels of smoking explosives into the interior of the fortress. In many shots you see the satchels flying high (VERY high) over the fortress walls to land inside. Unlikely that the strength of a human arm alone could catapult them THAT far up.
Continuity mistake: At the end of the film Alain (Van Damme) picks up a heavy machine gun and goes roaming about the ruins of the destroyed Legionnaire fortress. During one shot you see him opening fire on a group of Arab horsemen below. Strange thing that he never hit a single one of them at such close range! And even stranger, why didn't the Arabs return fire and kill him? He was a sitting duck out there on high ground.
Plot hole: As the ambush at the waterhole concludes and the Arabs withdraw (having captured the Legionnaires' supplies), the Arab leader Abd El-Krim rides up in open view on a high rock to survey the shattered Legionnaire forces. Heh, why didn't anyone think of getting a good, clean shot at him then?
Continuity mistake: During the penultimate Arab assault on the Legionnaire fortress, Macintosh gets wounded in the eye and has to tie a makeshift cloth bandage across his face to stem the bleeding. The bandage is clearly stained with blood after the battle, but in subsequent scenes it's clean.