When your new-fangled effects are too new-fangled
Most special-effects "fix-its" -- when the boom mics or crew members are caught in frame, when the shot is out of focus, or when wayward extras need to be removed from a scene -- simply slip by unnoticed.
Then there are times when things go totally off the rails. Such was the case for the X-ray-scanning sequence in Paul Verhoeven's Total Recall. In the scene, Arnold Schwarzenegger's Douglas Quaid walks behind a futuristic X-ray screen and becomes a computer-animated skeleton. Early motion-capture techniques, similar to the technique that brought Gollum and the Planet of the Apes apes to life, were used during filming to capture Schwarzenegger's walk cycle. But the outsourced effects work was… junk. Schwarzenegger reportedly wore too many reflective balls, blurring his movements to the motion-capture cameras. Without usable data, Verhoeven's effects team had to resort to old-fashioned animation.