“We started the film without a script, without a cast and without a shark,” was how Richard Dreyfuss famously summed up the nightmarish production of Jaws, whose last-minute rewrites, technical hitches and sinking boats almost halted Steven Spielberg’s career before it had even begun.

Incredibly, Jaws was defined rather than destroyed by its arduous shoot. The presence of the murderous shark was implied through editing and music rather than excessive effects shots, while the absence of a finished script for much of the movie resulted in some of Jaws‘ most memorable lines – “We’re gonna need a bigger boat”, Quint’s bloodcurdling Indianapolis speech – were either improvised or partly written by the actors themselves.

As this article aims to demonstrate, starting a film production without a finished script needn’t spell disaster – but not having one can often prove extremely costly…

Sunset Boulevard (1950)

Billy Wilder’s unforgettably cutting film noir is famous for its sparkling and oft-quoted script (“I am big, it’s the pictures that got small!”) – but remarkably, Wilder and his writer/producer collaborator Charles Brackett began filming Sunset Boulevard with only the first third of the screenplay complete. Unusually, this wasn’t due to poor planning or production deadlines, but as a means of sneaking the movie’s tricky subject matter past the film censors and its studio.