Visible crew/equipment: When the O'Hara family does their prayer you see two boom mike shadows on the ceiling. (00:14:15)
Visible crew/equipment: When Mammy catches Scarlett trying on a pretty bonnet when she is supposed to be in mourning, when the camera pans wide to show the room, in the mirror on the wall behind Scarlett you can see the shadow of the grip holding the mic above Scarlett.
Answer: If she looked rich she could trick him into thinking she wasn't marrying him for his money.