3. Towne's script originally had a happy ending.
As you might be able to tell at this point, it was a contentious production, with Evans, Polanski and Towne fighting pretty consistently throughout. The writer and director worked on the script for two months together in the spring of 1973, a script that Towne thought needed no improvement. Polanski recalled to Peter Biskind how they would sit there with Towne's dog as the scribe smoked a pipe: "The goddamn dog would lie on my feet in this hot room and drool. Bob would fill his pipe and smoke, and this smoke filled up the room -- it was really a hard experience for eight weeks of that. Bob would fight for every word, for every line of the dialogue as if it was carved in marble." And Towne confirms that, "We fought, every day, over everything. Names. 'What's her name?' 'No, it can't be that, it's too Jewish.' " They came into conflict on everything from whether there should actually be a scene set in Chinatown to the noirish voiceover narration (which Polanski would cut in post-production, winning that particular battle). It was the ending that was the major bone of contention between the two, however. Towne had originally written a conclusion where Evelyn survived and killed her father. But Polanski was in a darker place -- it was his first time in L.A. since the murder of his wife Sharon Tate four years earlier -- and later told Biskind "I thought it was a serious movie, not an adventure story for the kids," while Towne later summed up the director's argument as "That's life. Beautiful blondes die in Los Angeles. Sharon had." Nevertheless, the scribe refused to budge for the longest time, but says that Polanski eventually persuaded him to write an alternate version: "Roman said 'I want it written this way,' and I responded ‘I think it would be very bad if I wrote it that way.’ He said 'Well, try it anyway.' So I did, and brought it back to him and said ‘See, it’s so melodramatic.' Roman said 'No, it’s perfect.' We said more about it, but not much. That was that." And so Noah Cross survived, and Evelyn is killed with a shot through the eye by the police -- a nod, Dunaway says, to the story of Oedipus.

Chinatown John Huston
4. Jerry Goldsmith wrote his legendary score to the film in only ten days.
Originally, Polanski had hired the relatively unknown Phillip Lambro to pen the score, which the director wanted to sound like music from the 1930s. Evans and Towne weren't convinced, but it was only when Polanski invited his friend, Polish composer Bronislau Kaper, to see the film, and Kaper told Evans "It's a great film, but you have to change the music," did it become a pressing concern. Polanski was happy with it, but left L.A. to direct an opera in Europe for a few weeks, and the writer and producer decided to act. Jerry Goldsmith was brought on board to write and record an entirely new score, on an insanely tight schedule of ten days. According to Towne on the DVD commentary for the film, Evans suggested the use of the trumpet as a leitmotif, while Goldsmith said, in the CD liner notes that, "When I first saw the film I immediately got a flash as to the orchestral fabric I wanted. I had no idea musically what it was going to be but there was a sound in my mind and I wanted to use strings, four pianos, four harps, two percussionists, and a trumpet." The result was an instant classic. You can hear snippets of Lambro's original score in the film's trailer -- see below.

5. There was an aborted third film in the Jake Gittes trilogy.
Sixteen years after "Chinatown," Towne, Evans and Nicholson reunited for a sequel, "The Two Jakes," which picked up with Gittes in 1948 as he's hired by Jake Berman (Harvey Keitel) to catch his wife cheating on him, only to see Berman kill the other man, in a plot set against the backdrop of the oil industry. Towne wrote the script and was going to direct, and the original, ill-conceived idea was that Evans himself, who hadn't acted in thirty years, was to play the other Jake. But a few days into filming, Towne realized that Evans didn't have the chops required and fired him, causing sets to be torn down and lawsuits to fly. Nicholson stepped in as director, for the first time in a decade (it's perhaps no coincidence that he's not done it since), and the film was a box-office flop and picked up mostly hostile reviews (there are, on reflection, things to like, but Nicholson is clearly no Polanski behind the camera and Towne's script is more self-conscious than the original). As a result, it put paid to a film that would have closed off the Gittes trilogy. There's an urban legend that the finale would have been called "Cloverleaf," and that its plot involving the construction of the L.A. freeway was repurposed for "Who Framed Roger Rabbit?," although Towne denies this, and 'Roger Rabbit' was actually released two years before "The Two Jakes," which seems to discount that completely. In fact, the script was called "Gittes Vs. Gittes," revolving around Nicholson's divorce from Meg Tilly's character from the second film. The actor told MTV in 2007 that it would have continued the thematic riffs of the earlier films as well as picking up with Gittes "We always planned on making three films. We wanted it all to be tied into elemental things. 'Chinatown' is obviously water. 'The Two Jakes' is fire and energy. And the third film was meant to be about Gittes' divorce and relate to air. It was meant to be set in 1968 when no-fault divorce went into effect in California. It was to be about Gittes' divorce. The secrecy of Meg Tilly's character was somehow to involve the most private person in California, Howard Hughes. That is where the air element would have come into the picture." Nicholson held out hope at the time that it might happen, but two years later, Towne expressed doubt, saying "anything is possible, but I doubt it."