Remember how strange the final episode of Seinfeld was?

In Hollywood, endings are big business. And for good reason. No matter how good a film, telemovie or TV series is, if the ending fails to satisfy, audiences will label it a dud.

It's well known that the producers of Sex and the City took the unusual step of shooting three alternative endings to the final episode - primarily to help guard against "the real ending" leaking out. But what's perhaps not so well-known is that when it comes to the American movie industry not only will filmmakers shoot a range of endings, they also test them on the public before making their final decision.

So who gets to be in a test audience? Anyone. Test audiences are randomly recruited from movie queues and offered the chance to see a new yet to be released movie for free. The catch is that on seeing the film, participants need to fill out a survey detailing everything from what they thought of the characters to what five scenes they like least and best. And when it comes to reviewing the results, the movie studios take it very seriously.

Fatal Attraction was the 1987 thriller about a married lawyer (Michael Douglas) who has a one-night stand with a client (Glenn Close) only to end up being stalked by the woman when she takes offence to being "dumped".

The original ending to the film saw Glenn Close's character commit suicide. However, test audiences so despised her character (the psychotic, bunny boiling Alex), they indicated on their surveys that they wouldn't be satisfied unless she was properly punished for her sins. The producers decided it was important to keep audiences happy, so they re-shot the ending and had Close killed by Douglas.

In the 1997 comedy smash-hit My Best Friend's Wedding, Rupert Everett's gay character (George) was so popular with test audiences that his role was deliberately expanded and the film's ending was re-shot so he could be part of it, and take the dejected Julia Roberts for a spin around the dance floor at her best friend's wedding.

Speaking of Roberts, rumour has it the original ending of Pretty Woman saw Richard Gere leave her behind to fend for herself as a hooker. Charming! Needless to say, a fairytale ending was re-shot.

But it's not always so easy to re-shoot an ending, mostly because it means reassembling the cast.

Cult 1980s flick Pretty In Pink starred Molly Ringwald (Andie, the pretty in pink poor girl), Andrew McCarthy (Blane, the pretty boy rich kid) and Jon Cryer (Ducky, Andie's wacky best friend who is secretly in love with her). The film's original ending saw Andie get together with Ducky but test audiences were having none of that. They wanted Andie to be with Blane.

So the cast had to be reassembled in Canada to re-shoot the ending. There was just one small problem. Andrew McCarthy had already lost a lot of weight and shaved his head for his role in The Boys of Winter, a play which he was about to start. So producers made him wear a wig and, if you go back and watch the film, McCarthy looks suddenly gaunt in the film's final scenes.

Don't think it's just storylines that get re-shot after test audiences screenings.

Next year the remake of the 1966 classic film Alfie (about a Cockney womaniser) will hit the screens. Since Cher recorded the title song for the original film (American version), it makes sense that she was asked to re-record it for the remake. Not for long!

This year's test audiences reportedly laughed when they heard Cher singing and indicated on their surveys that her voice ruined the mood of the film. Cher has since been dropped and it's claimed Norah Jones and Joss Stone have been approached to re-record the tune.