He might be able to summon lightning from the skies and smite foes with his mighty hammer, but this latest comic-book outing bestows upon Thor an even super-er superpower: a sense of humour. It’s there from the opening seconds, when we find our Norse god dangling before some horned demon, whose portentous monologuing is undercut by Thor’s continual interruptions, as he slowly spins around on his chains: “Hang on a minute… coming round again.” For a relative newcomer to the Earth, Thor has clearly got the knack of 21st-century comic timing.

That’s the general register of this entertaining but frankly inconsequential Marvel movie. It’s what you’d call a “romp” – and one whose lurid 1980s-retro stylings bring it closer to the Guardians of the Galaxy end of the spectrum, though its spiritual forebears would also include Mike Hodges’ Flash Gordon, He-Man and the Masters of the Universe, and possibly Red Dwarf. Comic-book movies have spent a long time striving to be taken as serious, grownup entertainment but Thor: Ragnarok is almost an admission that you can’t play this material straight.

This is probably the wisest strategy with Thor. Despite his Avenger status, he has never felt particularly key to proceedings in the ever-unfolding Marvel Universe. His fantasy realm does not easily intersect with our own, and his last solo movie – Thor: The Dark World – was probably the weakest Marvel instalment to date. So this time they’ve brought in New Zealander director Taika Waititi, best known for lovable, considerably smaller-scale movies like Hunt for the Wilderpeople and vampire spoof What We Do in the Shadows. Waititi infuses proceedings with that familiar, generously self-deprecating Kiwi wit, nowhere more so than in his own scene-stealing voice turn as a cheery blue rock monster. He also unlocks untapped comedy reserves in Chris Hemsworth, who diffuses his character’s beefcake machismo with a quick tongue and a barely concealed insecurity – he’s like Ben Stiller in the body of Dolph Lundgren.

Thor’s family problems are at the root of this busy saga. His adoptive brother Loki (Tom Hiddleston) is up to his usual tricks, on top of which they discover they have an elder sister: Hela, the goddess of death. (Norse scholars look away now.) Played by Cate Blanchett, with emo eye makeup and spiky antlers, she’s like a Norse Maleficent. While she sets about tearing up Asgard, Thor and Loki find themselves stranded on a brightly coloured planet that looks as if it’s made from the discarded sets of 1980s TV shows. Its face-painted, thrift-store-coutured inhabitants could be refugees from New Wave synth bands. (The score is by Devo’s Mark Mothersbaugh, which makes this OK.) That the ruler of this planet is Jeff Goldblum with a blue stripe down his chin is entirely appropriate, if not particularly scary. He condemns the captive Thor to gladiatorial combat – where his foe turns out to be “a friend from work”. If you’ve seen the trailer, this is not a spoiler.

Tearing up ... Cate Blanchett as Hela. Photograph: Walt Disney Studios

Fans will be satisfied at the most fleshed-out performance of Hulk we’ve yet had in this Marvel universe, though Mark Ruffalo is charmingly confused when he’s being Bruce Banner. And rounding out the cast is Tessa Thompson, who turns up as a lapsed warrior from Thor’s neck of the cosmos, which is a useful coincidence. There are a great many corners cut, plot holes papered over, and laws of physics bent out of recognition in this movie, to be honest. And if you’ve sat through the past dozen recent Marvel movies, you’ll find the core elements very familiar – a rag-tag team of heroes (Thor unimaginatively dubs them “the Revengers”), an all-powerful antagonist, an impending apocalypse, and a set of essentially unkillable characters. Added to which, the liberal use of CGI and green screen makes for a visual flimsiness. Even the scenes set in “Norway” look fake.

But Thor: Ragnarok gets away with all of this because it’s so winningly, unpretentiously funny. It basically throws up its hands at its own ridiculousness and plays it all for laughs – and it gets them. The price of this irreverence is the possibility of taking anything that happens all that seriously – even the potential destruction of the Norse gods’ home (that’s not a spoiler either: it’s the title of the movie). There’s a potentially intriguing subtext about Asgard’s gilded spires – and by extension European civilisation – having been built on the suffering and riches of others, but, being a bit of a downer, it’s dealt with fleetingly. The romp must go on.