Other mistake: Dunnaway fires a warning shot next to her father to encourage him to leave the property. In the sequence just before he leaves she fires one shot and there are two dirt eruptions near his legs.
Other mistake: During the attack on the oil rig numerous members of Palance's crew are killed or wounded by grenade & rifle fire. When the attack is over there are no bodies on the battlefield.
Factual error: The oil "drill" is actually an oil rig, meant to pump oil, not drill for it.