It's hard to believe that this movie had ever been made, hard to believe that the cast could be so badly wasted despite the talent, and even harder to believe that the purest example of detached machismo in Hollywood couldn't pull off the role. John Wayne was a great actor, and not the hollow stereotype that he was often accused of being as his popularity waned. He might not have been one's ideal for delivering a comic line, but if anybody could force a line to have dry humor, it was he.
The script is the first disaster. The mock-Shakespearean lingo is for Shakespeare, who never set any of his plays in Mongolia. Here it is ludicrous (Chaucer would be in tune with the time, but few people understand Chaucerian English)! The costumes fail to convince one. Add to this -- Genghiz Khan was no hero; he initiated the most horrific killing spree of the pre-modern world. It's a big mistake to lionize a killer.
The great lore of this movie is that so many of the cast and crew died of cancer during some A-bomb tests near the location. That is sheer bad luck. Even without the calamity of cancer allegedly contributed to by nearby nukes, this would be a horrible movie, an embarrasment for all involved.