Schwarzenegger confirmed that the film was likely to happen -- starring Eddie Murphy as the pair's unlikely brother -- earlier this year.

Now it's been announced that screenwriting analyst Ryan Dixon will write the project with actor Josh Gad, the star of "South Park" creators Matt Stone and Trey Parker's Broadway musical "The Book of Mormon".

The announcement of Gad as a writer of the film puts a different slant on the production, with his previous work including stints on Jon Stewart's "The Daily Show", appearances on hit comedy "Modern Family" and having co-created forthcoming political sit-com "1600 Penn" with former Obama speechwriter Jon Lovett.

Meanwhile, the Austrian Oak had previously said that original director Ivan Reitman was also having an involvement in the comedy, and this now appears to be the case, with his company Montecito Picture Co. making the film with Universal.

It's one of a number of projects for Arnie, following his stint in politics as governor of California.

He's got "The Last Stand" with Johnny Knoxville and Forest Whitaker, "The Tomb" with Sylvester Stallone and "Ten" with Sam Worthington all due out next year.

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Ben Arnold writes for Yahoo! Movies UK & IE