 <unk> <unk> were used to ensure the safety of the actors , though the crew attempted to conceal or camouflage them for historical authenticity , as they were not then used by the Roman cavalry . <unk> playing soldiers attended a boot camp under the guidance of a former Royal Marine . Those actors portraying <unk> learned to fight by <unk> , not <unk> their weapons . <unk> reportedly <unk> four thousand costumes using authentic period materials such as cotton , linen , wool and silk , all of which were hand @-@ <unk> on set . Pullo was originally written to be a poor horse rider , a reflection that " Romans were notoriously bad horsemen , " according to Heller . However , Stevenson turned out to be " probably the best <unk> on the show , " so they rewrote this characteristic because bad horsemanship is difficult to fake . 
