Who says actors actually to be alive to make a movie? Oliver Reed died during the film's production, and the producers decided add a digital recreation of his face in during some of the scenes they really needed. (Source)

You know that big battle scene at the beginning? Well that's real fire, folks. The forest in England where the scene was shot was going to be deforested anyway, so Ridley Scott & Co. decided to help out a little bit and burn down some of the trees. (Source)

Oliver Reed (Proximo) was definitely a hothead. At one point, he supposedly challenged Russell Crowe to a fight. (Source)