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).
In the mid 50's, it was announced that Errol Flynn would be starring in his first TV series, a French Foreign Legion show which would have also gone by the title " March or Die" . It never materialised.