Ray Winstone travelled to Spain two weeks before filming commenced to get as deep a tan as he could in the time possible and to eat as much as he could to bulk up considerably. He called it "the best rehearsal time I've ever had in my life."
Reportedly the other actors were so stunned by the ferocity of Sir Ben Kingsley's performance that they occasionally forgot their lines and much of the fear in their performances wasn't difficult to act.
The boulder was made of fiberglass. A large net was kept open on the ledge of the pool so that if the boulder went over the pool, it would not continue down the hill into the village below. Additional shots involving the boulder were created digitally.