OK so Cary Grant saw the two baddies fire off the gun with blanks. Fine.
Eva comes out to inquire about the noise.. but how did the housekeeper not hear that gunshot?? I am wondering why she didn't know the gun fired blanks while holding Cary hostage.
plot hole or did I miss something?
Possibly the housekeeper dismissed the noise as something other than gunfire. She may not have even been in the house at that moment. She has no reason to have knowledge about the gun. She wasn't involved, and Van Damm himself didn't know the gun was fake, until Leonard fired it at him. Doubtful she knew who Kaplan/Thornhill was. He was simply a home intruder to her. She saw a gun lying around and picked it up.