An unemployed New Zealand rugby enthusiast got the job of a lifetime when he was asked to advise legendary Hollywood director Clint Eastwood how to make rugby look authentic in his film Invictus.

The movie is based on the Springboks' 1995 World Cup win.

When Julian Bristow heard about the film, he contacted Eastwood's office to offer his expertise for free, the Stuff website reported.

Originally from Hastings but now living in San Pedro, California, Mr Bristow plays fullback for the Los Angeles Rugby Club, of which he is also president.

After filming finished, the 36-year-old was taken up on the offer and asked to go over the hours of footage.

"I said, 'hell yeah, I'll do it', so I was going out to Warner Brothers every day and working out of Clint Eastwood's office. It was great," he said.

The highlight was sitting on a couch talking rugby with Eastwood, he said.

It was Mr Bristow's responsibility to add the right sound effects, commentary and crowd noise and ensure the film was historically accurate.

He said he was proud of the way the rugby turned out.

"We had some of the best rugby people in South Africa choreographing it and they [the actors] were all rugby players."

And although Mr Bristow offered his services gratis, he was paid for his work, he said.