The motto of the French Foreign Legion is "Honneur et Fidélité" ("Honour and Fidelity"), not "We are Hard but we are Just." This second phrase in more like "The Law is harsh, but it is the Law", the motto of the Disciplinary Company of the Foreign Regiments in the Far East.
No military leader would let troops become so disorganised as the Legionnaires become on the dunes. Troops in this type of formation are very susceptible to isolated attacks and are easy to pick off individually.
The animals used in the films are Bactrian camels from Asia not the single-humped camels from North Africa and Arabia. Perhaps they had trouble getting the correct animals but they hid the second hump very well. But, the Bactrian is much shaggier and stockier and the ones in the movie are indeed Bactrians, not Dromedaries.
When the Emir(George Regas) halts his caravan to "rescue" Ralph Forbes and Lester Vail from the grain pit,he twice shouts instructions in Greek instead of Arabic: This was the native language of Mr. Regas.