In the scene in the cave, Flint retrieves a rope from outside the cave, so he can fashion a string for the bow, to shoot the golden arrow. The bow is a modern recurve, and must be strung in a specific manner. After he has unwound the rope, the next scene shows the bow strung, with the arrow nocked, but the bow is strung backwards and will not only not shoot the arrow, the string will come loose from the bow.