Richard Harris and Charlton Heston did not get along during filming. Harris described Heston as "being so square that he must have fallen from a cubic moon."
Charlton Heston famously did not get along with Richard Harris, who frequently stayed up drinking into the early hours, and was often late on-set.
Shooting was ended early by studio executives, in the interest of controlling costs, before some important scenes were filmed. Charlton Heston offered to return his entire salary if the studio would agree to film the opening scene, the massacre of soldiers and civilians by the Apaches-, and some re-shoots. The studio kept Heston's paycheck, but never shot the footage he asked for.
Lee Marvin was Sam Peckinpah's initial choice for the role of Samuel Potts, but he wanted too much money. Marvin's agent suggested James Coburn for the part, and he ultimately got the role.
Sam Peckinpah invited Charlton Heston to accompany him on a visit to a brothel. Heston, a conservative family man, declined.