Lou Lumenick‘s 1.27.08 review of the recently-released El Cid DVD doesn’t mention a tidbit included in one of the making-of docs, which is that Charlton Heston didn’t have much affection for Sophia Loren during filming (and vice versa), and that one result of this discomfort (according to a female eyewitness who was around during the shoot) is that Heston avoided eye contact with Loren during their scenes together.

John Fraser, Charlton Heston in El Cid (pic stolen from DVD Beaver’s El Cid page)

Once you’ve heard this, the watching of El Cid takes on an extra layer of humor and intrigue. Heston does look away from her a lot.
Why the animus? Heston tended to be “a little rough” on his female costars at the time, but he also (a) resented Loren’s pizza breath (i.e., her eating Italian dishes between takes + not enough subsequent tooth-brushing and mouthwashing) and (b) the fact that Loren was paid the then-astronomical sum of $1 million by El Cid producer Samuel Bronston.
Which other famed costars in big, well-known movies didn’t get along? Or in any memorable film at all, for that matter? I vaguely recall reading somewhere that Vivien Leigh didn’t much care for Clark Gable during the shooting of Gone With The Wind, again over bad-breath concerns.