At then end of "Indiana Jones and the Last Crusade", Donovan agrees to let Elsa choose which cup might be the true Holy Grail. As we find out, she (and by extension, Donovan) chooses "poorly." Is this an intentional tactic on her part to get Donovan out of the picture so Indy can select the correct cup without gun-wielding Donovan lurking over his shoulder?
If she's not trying to get Donovan out of the picture, what reasons does she have for selecting the false grail, other than it just being an honest mistake?