production, director Steven Spielberg (I) (qv),  accompanied by friends Martin Scorsese (qv), George Lucas (qv)  and John Milius (qv), visited the effects shop where "Bruce" the  shark was being constructed. Lucas stuck his head in the sharks  mouth to see how it worked and, as a joke, Milius and Spielberg  sneaked to the controls and made the jaw clamp shut on Lucas head.  Unfortunately, and rather prophetically, considering the later  technical difficulties the production would suffer, the shark  malfunctioned, and Lucas got stuck in the mouth of the shark. When  Spielberg and Milius were finally able to free him, the three men  ran out of the workshop, afraid theyd done major damage to the  creature.