Gene Hackman had been experiencing pains in his back. The film's insurance company refused to allow the shooting to continue because a permanent injury to Hackman could have cost it a lot of money. The insurers suggested shooting the film somewhere in the deserts of the United States. But the color of the sand dunes in Agadir is not the same as the color of the sand in Nevada. Several big American transport planes were used to transport tons of sand from the Agadir dunes in order to camouflage the sand of Nevada. (Source: Beyond Casablanca, Page 131).
El Krim is based on the Morrocian revolutionary Abd el-Krim (1882-1963), the leader of a large-scale armed resistance movement in the Rif, a Berber area of north-eastern Morocco.
The Legion uses French military equipment and customs. Yet in one scene, when the new recruits are awakened one morning, an American bugle call (reveille) is used.
Minister: [Reassuring Marneau that, in spite of Major Foster's lack of cooperation, the Foreign Legion will be used to help provide military security for Marneau's intended archaeological excavation at Erfoud]
We can certainly risk a few Legionnaires for France. After all, they are mostly foreigners.
Simone Picard: [Marco has cleverly found a way to get from the troop car to the first class train car]
What else can you do besides steal and climb like a monkey?