We've seen some particularly inept ways to wrap up martial arts films, but the 1982 magical kung fu flick Ninja In The Dragon's Den takes bad movie endings to zeniths that have not been replicated in the last 30 years.
In the finale above, the protagonists square off against an evil master who walks on stilts and spars by palming a cannonball. This is puzzling, but barely worth mentioning in the grand scheme of things.
No, the true action comes at 3:30, when the douchebag heroes unveil their secret weapon, whereupon the movie convulses to a conclusion. The scene is safe for work (but not your mental health).