Corrected entry: When the guard at the Louvre is pointing the gun at Langdon, Sophie takes the 'canvas' painting of the "Madonna of the Rocks" off of the wall and uses it as a hostage - if the guard doesn't drop the gun she will supposedly tear the painting apart. However, the real painting has a solid wood back to it, making it too heavy to lift, let alone tear it apart.
Myridon
19th Nov 2006
Correction: While it's true that the painting was originally on wood, it was later transferred to canvas according to Wikipedia ( http://en.wikipedia.org/wiki/Virgin_of_the_Rocks#History_of_the_paintings ) Quote: "The Louvre version was transferred to canvas from the original wooden panel but the London painting is still on panel."
Myridon