During the Vietnam War, an elite tactical unit is sent to search for a missing group of Green Berets – only to stumble on an improbable valley of dinosaurs instead. Primitive War is high concept populist cinema, produced with a close eye on drawing the best possible visual effects out of modest budget. From a purely technical standpoint it is an impressive achievement in film production. From a more creative perspective? It is an unwieldy disappointment.

With such a pulpy concept, one would expect Primitive War to be a knowingly ridiculous exercise in pleasing a crowd. Instead director Luke Sparke and co-writer Ethan Pettus aim for a higher, more involved sort of science fiction thriller. There is a point midway through the film when it becomes clear this 90-minute exercise in violent mayhem is actually a 133-minute attempt at serious, grown-up cinema, and for this viewer at least the realisation sucked a lot of joy from the experience. The visuals are there for over-the-top fun. The screenplay, based on Pettus’ novel, is not there for where the film is aiming.

It is also a shame that the film, an Australian production, is so emphatic in seeking an American audience that it does not contain any Australian characters at all. Instead a thinly-drawn set of stereotypical army rangers go through the motions, doing what is expected of them. They are sufficient, but are hardly interesting. Lead actor Ryan Kwanten is a decent performer, but like American co-star Tricia Helfer he has very little to challenge him or to draw out an interesting character. Jeremy Piven appears as a commanding officer in what is essentially an extended cameo, and he plays the part with one eye on a pay cheque and another on the clock.

For a film set in Vietnam there are precious few Vietnamese people on the screen, just dinosaurs and – somewhat oddly – Russian mad scientists. There is also a fair amount of casual racism, which might be true to the period but still feels rather gross and unpleasant to watch.

The film comes peppered with songs from the standard Vietnam War movie playbook, and it’s hard to tell if the liberal use of Creedence Clearwater Revival and the Spencer Davis Group is intentionally ironic or creatively lazy. Certainly it is a little awkward that Primitive War is set in 1968, at least a year before most of its soundtrack was original released. Then again, the story does involve time travel – who is to say that the songs didn’t arrive in the same way as all of the dinosaurs?

It is heartening to see an Australian production get such healthy funding and international distribution, and to aim for mainstream entertainment in competition with Hollywood. We deserve to see more of this nature in the future. We can just hope that future attempts will be grounded with a stronger script than we got here.