Hawks wanted so much to have Paula Prentiss as his leading lady that he even considered to move the production to M-G-M, where she was under contract.
Cary Grant turned down the lead role because he was 58 and the leading lady Paula Prentiss was only 24.
When Cahiers du Cinéma requested statements from a selection of auteur filmmakers from around the world for inclusion in the magazine, Howard Hawks simply sent a production still from Man's Favorite Sport of Rock Hudson up to his neck in the lake with no explanation.
Ursula Andress was the first choice for the Maria Perschy role.