This is one of few special fx knives used in the film. This particular knife is made entirely out of aluminum. There is a small pin hole that has been drilled all the way through it, tip to tip. This was made this way so that it can be slid on a zip line to the target and hit where intended. One end of the line was off camera, the other attached to the actors with a piece of balsa wood for the knife to stick in. The special effect coordinator told be he actually used a slingshot to launch the knives. You can see a small amount of tar or plumbers putty still on the tip. This putty allowed for the knives to really stick.
