The shockingly - one might fairly say unprecedentedly - successful Mexican import Instructions Not Included possesses a title and the skeleton of a plot (womanizer has an illegitimate child dropped on his doorstep, must take care of her) that makes it absolutely obvious what kind of film it is: a warm and cuddly two hours in which a shitty, self-absorbed bachelor learns to love other beings because of his darling infant daughter. Spoiler alert: it's not that movie. Also, the Spanish title, No se Aceptan Devoluciones, translates (saith Google) as "No Refunds", which is a whole hell of a lot better and more craftily suggestive of the plot.

To be sure, the film includes that movie, but it includes a great many movies, and by the 20 minute mark, it's already on the third one. Prior to that, we have experienced a wacky slapstick prologue in which robust Acapulco father Juan "Johnny" Bravo (Hugo Stiglitz) teaches his young son Valentín (who will be played, as a grown-up, by the film's director and co-writer Eugenio Derbez) how not to be scared, largely by plunging the child into a series of traumatising situations that serve the exact wrong purpose. For instead of having no fears, Valentín has all of the fears, which he visualises in the form of wolves ready to tear into him if he goes up that ladder/into that pool/by that spider/etc.

The biggest fear of all, he confides in truly weird cut across 25 years, is the fear of commitment. But the montage of random, family-friendly fucking that begins in this second face of the film, the "slapstick sex comedy" face, is brought to a close when one of Valentín's conquests, the American hippie Julie (Jessica Lindsey), arrives on his stoop with a baby girl that the dissolute chauvinist fathered, and leaves before he has a chance to react. He's so angry that he sneaks into the United States illegally just to dump the baby back at her feet, but something magical happens, and he realises that he's ready to be a father. Except that, now he has an American-born infant with him and no proof that he's related to her, any attempt to get back across the border would be suicide and a half.

At this point, the film skips ahead a few years, to find Valentín a hugely successful Hollywood stuntman, and his daughter Maggie (Loreto Peralta) a criminally darling 7-year-old with more fanciful ideas than you could possibly know what to do with. Valentín feeds these fantasies, spinning a ridiculous life story for the absent Julie involving spying and trips to the moon, and he spends a huge portion of his improbably high wages on buying every imaginable toy for Maggie. At just about the same time he gets a hugely discouraging diagnosis from the family doctor - which he deliberately hides from everybody besides his producer, Frank Ryan (Daniel Raymont) - Julie shows up, with her partner Reneé (Alessandra Rosaldo), looking to re-enter Maggie's life and, if possible, sue to get custody and bring the girl back to New York.

That's still two entire genre shifts from the end yet, one of which involves the single biggest tonal shift that I've seen in a 2013 movie, but let's go ahead and slow down to catch up with what the hell we just read. Instructions Not Included is assuredly not the bland, totally generic thing it looks like from the outside: the precise opposite of that, in fact. It's a florid, ADD-afflicted magpie of a film, including every plot point and emotional register it can, switching from smutty sex jokes to buoyant kiddie-flick slapstick to the treacly warm dramedy of a Very Special episode of an '80s family sitcom within the span of a shot, let alone a scene. It has intimations of political commentary (that it pointedly steps back from) and a weird fantasy idea of what the movie industry is like; it becomes a sober and serious custody battle drama that takes a sharp turn at the last possible instant into a shameless tearjerker. If it were American-made, I like to think of Lee Daniels getting his paws on it; it has the same register of anything goes creativity and disregard for traditional notions of emotional coherence that I respond to in his films.

I also suspect that it would be a better film in that case, given how weirdly Derbez mismanages the thing. I gather that he is a highly-regarded comic mind in Mexico, but Instructions Not Included isn't entirely a comedy; it has comic elements, but it has elements of everything else, too, and the jokes are more of a cute and warm register than actually being funny. Though I'll allow the possibility of a cultural or language gap between me and the film.

Anyway, the comic parts of the film, outside of the sex farce elements and the brief scenes of Valentín plying his trade as a stuntman (doubling for a powerfully unamusing parody of Johnny Depp), are mostly stuck in the "rubber-faced clown and darling moppet" mode that Roberto Benigni ruined for the rest of time with Life Is Beautiful. It actually works in this film, more than I'd have expected, thanks largely to Peralta, a distractingly good child actor (who, even more distractingly, looks like Kristen Bell's clone); not as much to Derbez, visibly ten years too old to be playing a developmentally arrested manchild specifically indicated to be in his mid-30s, though his clowning actually does add to the tenderness of the relationship, rather than just playing as cloying.

In fact, were it just for the candy-colored father-daughter relationship, I could see myself waving Instructions Not Included through, on the grounds that it's effectively sweet, and we need sweet things, just as much as we need anything else. Even the ginned-up conflict between Bitch Lesbian edition Julie and Valentín "works", though I should have preferred it working in some other movie than this one. The whole affair, though is so unevenly handled, slurrying emotions in a way that feels careless rather than cleverly unconventional, and the whole thing is about as visually drab as anything with this many bright colors and painfully quirky touches in the costumes and sets could manage to be. It's a slack movie that tries to coast on hamfisted emotional manipulation to make the viewer feel feelings, and ends up (particularly on the back of a crass, overwrought ending) playing as superficial and insincere at far too many key moments.