Two cases come to mind:-
For the past year, I have been trying to locate a film shot in Yugoslavia about WW2; I was sure the word BRIDGE was in there but all searches proved fruitless. You can see why; the title does not feature BRIDGE.
The other case happened late last year; I was searching for a book on line and in the book stores certain that the cover showed a man in a monk's cowl; again I was wrong, the reason why I was wrong is that I was writing my Mondoria story http://www.amazon.com/dp/B007XX5LVU which is set in Medieval times and had the image of a hooded figure fixed in my mind, the reason for this image is I based the main character on the game "Thief."
The irony here is that I had often gone to Waterstones to check the Warhammer books out and been able to go straight to the spot on the shelf where the book had been placed, but not registering with what I thought the cover was like, I replaced the book; I later bought the book when I went for the correct book
The cowled figure on the book was not linked to the cover of Chronicles of Mark Johnson book 2 http://www.amazon.com/dp/B00BO04Y20 at this time b2 had no cover in mind and the cover wasn't made until early this year.