For the famous The Last Supper scene, because the number of homeless people wasn't enough to match the actual amount of men present at The Last Supper, Buñuel made three crew members dressed like beggars, appear on the photo, and then disappear.
The script was initially approved by the Spanish authorities with a few minor changes. They had no opportunity to view the finished film until it played at the Cannes Film Festival where it won the Palme d'Or. Nevertheless they were sufficiently horrified by what they saw to ban the film.
Conchita Buñuel said the costumes in the film were authentic. "We scoured the outlying districts of Madrid for them, particularly under bridges, giving poor people new clothes in exchange for their rags, which were then disinfected but not washed."