In a world where Scary Movie, Date Movie and Epic Movie are considered funny...

In a world where movie audiences know more and more about film production...

In a world where Robert Downey Jnr can do anything he sets his mind to...

Tropic Thunder gets everything right.

You see, the problem with the Movie movies is that they think recreation plus exaggeration makes it a funny parody. What Flying High/Airplane and The Naked Gun movies and Spaceballs knew is that you have to also be the kind of film you are parodying.

Now this film is also about the making of a war film, but it gets away with it because it's part Apocalypse Now and part Heart of Darkness - the making of Apocalypse Now. But funnier.

So we have references to many, many war films - including Platoon, Full Metal Jacket, The Deer Hunter and The Thin Red Line - but there is also parody of "making of" documentaries, celebrity riders, method acting, shooting on location, insane agents, diabolical producers, effete  British directors, trailers, award-worthy films, celebrity cameos, celebrity endorsements and product placement (a bug bear of director Ben Stiller that stretches all the way back to Reality Bites).

At the heart of it is a parody of war films, though. The deranged vet. The drug-addled psycopath. The over-prepared first time soldier. The determined hero. The waxing philosophical sergeant who nobody really understands. There's talking about the girls they left at home - uh, Jennifer Love Hewitt and... Lance Bass. There's trying to replicate an old maneouvre to get them out of their newest situation. And there's the modern day version of the Viet Cong who turn the making of the movie into a real "war zone".

Ben Stiller as an actor brings what you expect. Ditto Jack Black. Nick Nolte, too. Matthew McConaughey, the same as always.

It's Robert Downey Jnr playing an Australian playing an African American that is truly outstanding. And bald-headed Tom Cruise with a middle-aged paunch and hairy arms practically steals the show. Well, if Downey didn't already have the show under his arm while he runs away with it.

The opening minutes of the film are outstanding - it's almost impossible to tell the film has started, because it opens with an ad for a new soft drink and only when the fake trailers start is it clear Tropic Thunder has started. Well, not Tropic Thunder - but the making of Tropic Thunder. Which in the film is called Tropic Blunder. Get it?

Oh, also? Downey Jnr's Australian accent is superb!