Revealing mistake: At one point Charles Bronson wields a rocket launcher, the type which is a one shot disposable variety that comes pre-loaded with the rocket inside the launcher and it cannot be reloaded. The problem is, before he fires, he swings the launcher so the audience can plainly see there is nothing in the launcher just before he fires.
Revealing mistake: When Frank Bauggs is falling from the building, he is a very obvious dummy. His body limps around too much. (00:50:45)
Revealing mistake: A bunch of seedy individuals are gathered, weapons in hand. Unbeknownst to them, though, deadly ninjas are creeping by, with all the speed of fast-forwarded footage. The problem, besides how obvious the trick is, is that it also features a visible jump cut; you can see the foliage change position literally from one frame to the other during the same shot. (00:01:30)