Watching Tongan Ninja is like watching a movie so deliberately bad, it's good! Which is not surprising, given that the creative brains of Jemaine Clement and Bret McKenzie behind Flight of the Conchords, had a hand in crafting the zany scenes, crazy dialogue and mind-boggling tongue in cheek action sequences. It's like watching a kid's cartoon come alive, though it comes with a tinge of unexpected violence as well to make it more adult.
The basic structure follows that of Bruce Lee's Way/Return of the Dragon, where a martial arts practitioner get sent to protect a restaurant from thugs who come asking for protection money. Sam Manu plays Sione Finau aka Tongan Ninja the titular character, whose tragic background of his father being killed by a fish haunts him into adulthood. Growing up in a Pacific island where he learns his ninja skills, he gets sent by his master to New Zealand to help a friend in need, represented by Miss Lee (Linda Tseng) whom he falls in love with.
You know it's gonna be mindless fun with slapstick humour when the villains are caricatures such as Knife Man, Gun Man and his arch-nemesis Action Man (played by Jemaine Clement himself) with whom is under the same ninja tutelage. The fights don't take themselves seriously, as it really hammed up every cliche you can find in bad action movies. From funny character names to funny action moves coupled with cheesily bad special effects, everyone's acting is really over the top, and therein lies the fun factor when watching the movie, complete with spaghetti western styled dialogue and dubbed voices that are never in sync.
What also worked here are the zany song and dance sequences, which acted as a precursor of the later collaboration between Clement and McKenzie. In fact, if you pay attention to the lyrics that are sung during these sequences, that's half the fun already as you're likely to have been chuckling along.
So don't expect quality production values with polished acting. You can tell these folks had a lot of fun spoofing the genre and probably had a great time on set, and this shows up in the product in all honesty. It doesn't bite off more than it can chew, and provides for some really enjoyable entertainment.