The prince retrieves the very important item that was stolen from DaVinci. This is the Mona Lisa rolled up and stuffed in a tube. Problem? . . . The Mona Lisa was painted on wood. Oops.
Very true...a big thing was when someone made a reproduction of the Mona Lisa on silk and sold it to a museum. They caught him, because it was painted on wood.
Just a thought... I paint sometimes and frequently, when a picture means a lot to me, I'll paint more than one copy 'just in case' so regardless of what happens to the original, I'll have one for just my own enjoyment. They say Leonardo used to draw page after page of just hands/eyes/whatever to get to the skill level he reached. The canvas Mona Lisa could have just been a personal copy he made that was destroyed before anyone found it.