Cinema's biggest improvised gamble?

Men in Black III, which opens in May, apparently began shooting without a finished script. Specifically, no third act had been written by the time cameras started rolling. Special-effects supremo Rick Baker (who had also worked on the previous instalments) told Empiremagazine: "It was a crazy production. We had a writer actually on the soundstage writing the words moments before the guys had to say them."

Apparently, the film was shot in a rush to exploit the window in the busy schedules of Will Smith, Tommy Lee Jones and director Barry Sonnenfeld.

This might sound unprecedented and foolhardy, but it's more common than you might think. Swathes of Iron Manwere improvised by Robert Downey Jr and director/ co-writer John Favreau to make up for an incomplete screenplay; Transformers IIstarted filming with an unfinished script because of the writers' strike; Terminator Salvationsuffered from many plotholes, probably because it was quickly rewritten before filming because the official script was leaked; and the unwieldy Pirates of the Caribbeansequels also started shooting without scripts.

Improvisation can work in films, of course. Robert Altman, Mike Leigh, Christopher Guest and Judd Apatow have built careers on it, in diverse films such as (respectively) Short Cuts, Secrets and Lies, Best in Showand The 40-Year-Old Virgin. But – as anyone who has attended a comedy improv night can tell you – this sort of narrative without a safety net is a big risk. With a budget exceeding $200 (€151) million Men in Black IIImight be cinema's biggest improvised gamble yet.