Do the sea monsters speak Italian or do they have there own language? All of the sea monster names seem to have Italian meanings, but they don't understand certain Italian words and use them out of context, for example, stupido. Other times they do use Italian words, for example, andiamo, in context. And if they do have their own language, how can they communicate with Porto Rosso inhabitants otherwise?
WMG: Luca is set in Liguria, which has its own language that was once common but has been in decline. It's close enough to Italian that it's understandable, but naturally there will always be misunderstandings. The sea monsters likely speak an old version of Ligurian, and since many were averse to visiting the surface, they don't go up on land enough to learn how words change. "Stupido", in its old form, meant 'amazed or stunned'. Alberto and Luca probably thought 'What's wrong with you, stupido?' means something like 'What's up, hotshot?'.
Also, Alberto uses the phrase "Andiamo" properly, there's nothing saying that he does so knowingly, or if like "What's wrong with you, stupido" he's only saying it because he overheard some humans saying it before.
Luca does read off the "Vespa è libertà" text on Alberto's Vespa poster as "Vespa is freedom", and the letters he and Alberto send to each other in the follow-up short appear to be composed in (very shoddily written) Italian, as if to imply that's what the characters are actually speaking and that most of it is being translated for the sake of the audience.
One-Armed Massimo
How come Massimo doesn't have a prosthetic arm, even a crude one?
Cost, most likely. Either that, or he just never saw the need for one as he got by just fine.
It's worth noting that Massimo is born without an arm. Most congenital amputees have already developed the dexterity necessary to get by since they've had the condition all their lives.
Also, plenty of people born without limbs are so used to not having one that getting a prosthetic is more hassle than help.
Sea Creature "Wet vs Dry" knowledge
How can a sea monster who's lived his entire existence underwater comprehend the concept of "wet" vs "dry"?
Luca seemed to have awareness of it. His grandmother even confirmed she's been through "the change" before, so at the least he was aware of/taught the difference wet v dry.
The same way any of us comprehend the idea of being spaced despite never having experienced it: we’re taught what air is, that we’re immersed in it, why our bodies need it, and that there are places that don’t have any, so we can vaguely understand what would happen if we were tossed into space. Luca has been told never to leave the water, so he knows there’s a place without water and has probably heard it referred to as “dry”.
Transformation Incontinence
How voluntary is the transformation? Luca and his parents seem to indicate you have no control becoming human-looking when stepping out of the water, but the morning after the duo meet Giulia in the treehouse Luca and Alberto were still in their sea monster forms even though the rain stopped long enough ago for the sky to be blue, and likewise near the end of the film when the rain stops all of the sea monsters remain in their sea monster forms. Likewise, how can Luca and the others dry off so fast? They just slap the moisture off their skin and they immediately turn to human form. Yet near the end they seem to have no problem retaining their sea form when gathered together for dinner.
It's shown to be completely involuntary. While the rain had stopped in both of those cases, they were probably still wet and hadn't fully dried off (in the first case, you can see them desperately shrugging off the remaining moisture before they revert to human form). In regards to the ending scene, it was continuously light drizzling, which was keeping them in their sea monster form. We don't know much regarding sea monster biology, but from what little we can gather we can infer that their skin/scales simply absorb water much better than human skin.
Shouldn't tears transform him?
When Alberto cried, how come the part of his face that got wet from tears didn't revert to sea monster form? Is the body immune to water that comes from within?
If one rewatches, the film was actually very deliberate making sure no tears came into contact with his face; only at the very end when Luca is leaving on the train do we actually see tears go down his cheek but by then the rain has already transformed him.
Sea monsters are hard to avoid or aren't they?
How has no one ever just gone swimming and seen the sea monsters?
Because they were too scared of them to go in the water. In the swimming portion of the Portorosso Cup, there were fishermen lined up with boats and harpoons in case sea monsters decided to attack the competitors. If they needed this much security to swim, there's no way they would have dared to do it leisurely.
Also the sea monster "village" is beyond Alberto's island which is already considered "haunted" and it's quite a distance from Portorosso. It's unlikely someone is going to take a boat out that far to do some casual swimming and see them.
And in the event a human does try to go swimming near where the sea monsters live, they'd just hide until the swimmer left.
Time Period
Just what period is this movie set in?
Cassarosa has said in a tweet the movie is set in 1959, though admittedly a handful of objects make it a bit of an Anachronism Stew - movie posters from 1953-1954, Luca and Giulia watching the moon landings, and the song "Il gatto e la volpe" which is from 1977 (though this could be HandWaved away since it's part of the soundtrack and not In-Universe. Best bet? Alternate Universe.
My guess is that they're in a period time set after 1969 but before 1978. As far as some of the other anachronisms go, that could be explained by the location, as some things didn't achieve or, rather, leave cultural relevance in some locations until much later.
How did they handle THAT?!
How did the fish people handle peak boat/ship season, especially during the two world wars? And that is not counting the future advancement of submarines and their sonar...
Global maritime traffic actually decreased during the world wars (not many civilian vessels venturing out far from port due to the threat of enemy attack), and Portorosso is a small town that doesn't appear to have been a major military base or strategic priority target (unlike the bigger cities like Genova). So if anything, those two periods would have been a more peaceful time for the sea monster village. As for regular, peacetime ship traffic, as mentioned above, the village appears to be pretty far from Portorosso. And the film is set in the 1950s or thereabouts, when sonar is still relatively new and not commonplace outside of military vessels (or at least not as widespread as today).
They handle it by being extremely careful. Luca's mother mentions early on that boats weren't nearly as frequent when she was younger as they are when the movie is set.
Those parents are weirdly not there
Daniela and Lorenzo spent the movie terrorizing the children of the town by soaking them wet. Shouldn’t there be angry and/or annoyed parents attacking them, chasing them, and calling them Italian insults such as ‘’Pazze!’’ (Lunatics). Where are those parents who should be chasing Daniela and Lorenzo away from their children?!
The parents are either busy with their daily activities, or dismiss the water-splashing antics as typical summertime play.
What they do isn’t anything THAT bad or dangerous; they mostly just toss the kids harmlessly into the fountain. The kids probably don't dislike it enough to tell their parents or fear for their safety.
Blowing bubbles, how?
At the beginning of the movie when Luca is bored watching his "flock", we see him blowing bubbles to amuse himself. What he is shown doing requires some kind of "space" that has collected air that can be blown out through his mouth to form a bubble. How does the native sea-monster "breathing" work so that it would allow Luca to blow bubbles like that?
Fish owner here: some fish have both gills equipped for breathing in the water and lungs equipped for breathing on land. The process of breathing is still an intake of oxygen and exhale of carbon dioxide like it is on the surface. These fish blow bubbles all the time. It’s possible that the sea monsters in the movie have a similar makeup?
Walking on water
How are Luca’s parents so good at walking on the surface? As we saw with Luca he had no clue how to walk when he went to the surface and even though it didn’t take him long to learn it still took effort. His parents, however, walked onto shore like it was nothing. You could say they may have been to the surface before in the past but if that’s the case then why would they be so freaked out by their human appearances? Luca’s mom acted like this was the first time they’ve transformed and attacked her husband like she didn’t expect him to look like that and freaked out at her own arms and hair.
Likely they've both been to the surface separately in the past and so neither of them have ever seen each other's human forms. Notably, Daniela didn't "freak out" at her own appearance as a human; she just remarked that it looked hideous.
Facial shape
Why do the others have prominent muzzles, while Luca has a flattened and more human-like face even in sea monster mode?
Luca's grandmother, while sharing very few other physical traits with Luca, also has a flatter and rounder face and muzzle. Even at the end of the film when the entire family is gathered in human form at the train station, Daniela and Lorenzo have huge noses in place of their prominent muzzles and Luca clearly shares his grandmother's comparatively small nose. If his face shape is not merely a trait of youth among sea monsters, then it's likely he inherited this from her.
First steps?
Why does Luca have such a hard time with legs and later Daniela says that she's "new to legs"? They do have legs in sea monster form unlike mermaids so you'd think they'd at least know how to use them, even if gravity was a bit difficult.
The sea monsters rarely use their legs in the water - they usually swim like fish using their tails. Luca did remark how he found the way humans swim using their legs as odd. Which is Fridge Brilliance: without a tail their sense of balance must be off.
How does he survive that?
How does Ugo survive all by himself in the deep if he regularly suffers heart attacks and needs someone to punch his heart to restart it? It's common enough that Luca's dad considers it a casual occurrence...
The intended interpretation is that he has a heart attack because he's up near the surface and there's less oxygen. In the deep sea he'd be fine.
No harpoons!
Why were Alberto, Luca, and Giulia smiling when both Ciccio and Guido refused to give Ercole another harpoon to kill both two of the sea-monsters?
Because they just "defeated" Ercole—literally and symbolically. Ercole's by far the human most hostile to them and he still fails to rally the town against them. They also just snapped his harpoon—his literal weapon against them—in half, and no one's giving him another. And he just lost the race to them, which he pathetically used as an excuse to posture his supposed superiority over a bunch of children. It's the complete dissolution of the social power of an Axe-Crazy bully as measured by that bully's own definition of his power; who wouldn't smile?
"Sea Monsters" slur
Why does Luca's species refer to themselves simply as "sea monsters", especially given that "land monsters" seem to be a Fantastic Slur they have toward humans? Don't they have a name for their own kind?
They just didn't have the chance to bring it up. In one of the deleted scenes from an earlier draft of the story Alberto corrects Giulia's use of the term "sea monsters" with the insistence that "the preferred term is Sea Folk," but that's from a very different version of the story.
Why was Alberto wearing the diving suit when Luca first met him? He didn't need it, and its weight and difficulty to maneuver when compared to his natural ocean form would only make it harder for him to gather his loot. Was he worried humans would see him? Was he just trying it on for fun? Did he see Luca swimming around his loot and decide he wanted to scare him? Did he even know it was a diving suit?
He probably found it just before that scene, and thought it would be easier to wear it onto the beach than to drag it along the ocean floor by hand.
Considering he's also needlessly carrying a harpoon with him and ominously corners Luca in a cave just to say "Boo", it seems that scaring him, as a joke, was also likely his intention.
Influence Ercole shouldn't have?
How does Ercole have so much influence over the town, despite not even being a well-liked Villain with Good Publicity or having criminal connections that make him too dangerous to trifle with? He also actively verbally and physically abuses the town children in broad daylight and none of the adults do anything about it. You'd think they'd have had him arrested or driven out of town a long time ago.
This is mildly WMG, but there's enough from Ercole's demeanor, clothing materials, and expensive vespa to suggest that his family may have money, and given that it's unlikely a Psychopathic Manchild like him is independently wealthy and influencial and no one else from his family is even seen let alone shown trying to interfere with Ercole's well-known Jerkass behavior, they clearly have no problem with how he acts. It's possible no one in town thinks it's worth confronting Ercole anymore because his family's influence means he doesn't face consequences anyways, which would explain Ercole's own social influence over the younger generation despite no one actually liking him—it's due to association with his family's influence, rather than any merit of his own—and how Ercole gets away with entering a competition for children every year, even though Word of God says he's over eighteen and it's almost certain the adults of the town know this.
Ercole says in his first scene that he paid for his Vespa with the prize money from winning the Portorosso Cup 5 times, presumably saved up over those years, but the rest of your points still stand.
Ercole may be a bully and a jerk, but he never really does anything that would make him legally punishable that the adults see. He makes to dunk Luca into a fountain, but that would be brushed off as harmless child's play. He takes the money Giulia needs to pay the entry fee for the race, but he gives it back very quickly, and it's never said that he would've evaded the consequences if Giulia had gone and told someone about it. He threatens to ram the boat the heroes are practising in, but it's diverted at the last second and would probably be written off as an accident. And then he starts to beat Alberto up in the middle of the night with no adults around who can see him.
Humans vs Sea Folk
On the relationship between humans and sea monsters: Do the humans of Portorosso hate and fear sea monsters because sea monsters have historically antagonized them? Or is it simply fear of the unknown? The depictions of sea monsters in paintings and statues around Portorosso aren't very accurate, and considering that Giulia initially believes they're a myth, it seems that humans know very little about them. We never see sea monsters willingly antagonize humans simply because they're humans—the worst Alberto does is steal human objects. Did some sort of conflict or misunderstanding happen between sea monsters and humans in the past that caused them to fear each other? Or do humans simply assume that sea monsters must be horrifying creatures because they've only gone off appearances and never bothered to connect with them?
It does seem as though the heightened paranoia about sea monsters seen in the present is meant to be blamed on Alberto stealing things from them — and considering how much stuff he has up in his tower and how long it's been since his father left him, he's probably been at it for quite a while. The fact that he is actively snatching things from the shadows along with the persistence of whatever old folk tales are still being told would be enough for the townspeople to be suspicious.
Umbrella Express
When it started raining during the bike portion of the race, how did Alberto arrive with an umbrella so quickly? If he was closely watching Luca the whole way, why would he have been running up the OTHER side of the mountain with the umbrella? Did he know or sense that it would rain and Luca would be in danger?
A variety of reasons and factors:
It seems reasonable to assume that Alberto was already on the island watching the race but remaining hidden.
Alberto states “the sky’s been leaking” when he and Luca wake up earlier, thus he’s familiar with the phenomenon and what clouds gathering meant.
When we see Alberto running by Massimo with the umbrella, the buildings in the background don’t resemble the ones seen near the finish line, hinting that he might’ve already gone some distance uphill by that point.
The turnaround point of the race is not at the top of Mount Portorosso but one of its lower ridges where the watchtower is. Remember this is a kid's race so it's not supposed to be that demanding.
How do they breathe?
How does Luca and everyone breathe on land in their natural, Sea Monster, form?
The most reasonable answer is that they breathe through their skin in their sea monster and probably their human form too. We don't actually see any lungs (or diaphragm) through Uncle Ugo's transparent skin which should have been surrounding his heart. When they shift to humanoids, it's unclear if they magically "grow" lungs and respiratory muscles like they magically "absorb" their tail or whether they just keep breathing through their skin and mimic "human breathing" by having some chest muscles that can emulate a diaphragm.
Mayhaps the Sea Folk are meant to be an extremely adaptable species when exposed to new environments? This would also explain why Luca’s ordinary-looking father looks so different from his see-through, anglerfish-looking uncle, despite them seemingly being from the same generation. Though this does mean that they don't just have the ability to "transform into humans", they have the ability to transform into whatever shape best suits the environment they're in. Might be interesting if they ever actually went to space...
Maybe they're a little amphibious?
Teaming up with Giulia
Why didn’t Luca team back up with Giulia to win the cup in the end? She didn’t seem to mind letting them have the prize money earlier on; she knew they wanted it to buy a Vespa, so having to split it up wouldn’t seem to be an issue. Between the two of them, they have two out of the three challenges down pat. Luca wouldn’t even have needed to risk exposing himself by swimming since Giulia was always going to tackle that part. Were they not allowed to have a team of two contestants, rather than one or three?
Earlier in the film after Giulia finds out that Luca is a sea monster, she insists that he leave Portorosso for his own safety. Maybe Giulia could've refused to let Luca on a team with her, but couldn't stop him from entering on his own. She couldn't exactly tell Señora Marsigliese WHY she didn't want Luca to race. The latter point about team numbers is a decent one too - in a team of two, one person would be taking on two segments of the race, which wouldn't be considered "fair" or equal - not in the same way that it would be with one person per challenge or one person completing all three challenges on their own.
What's more, Luca felt bad about having chosen to stand with Giulia rather than Alberto when the latter outed himself as a sea monster, especially once he learned about Alberto's father having abandoned him and that that was the source of his jealously and insecurities. Winning the money for the Vespa is Luca's way of making up for his betrayal, so he probably thinks the sincerity of the gesture would be tainted if he were only able to do it with the help of the human girl Alberto doesn't like.
Who helps Massimo
Who helps Massimo with his business while Giulia is living with his mother? Giulia says that she goes to Porto Rosso because her parents are separated every summer, but she is seen to be the only employee of her father before Luca and Alberto come up.
No one. Massimo just runs the business by himself when Giulia's not there. The main thing Giulia seemed to provide was a "delivery service" which was likely only offered during the summer while Giulia visits. Post-movie, Massimo now has Alberto to help.
Machiavelli tags along
Why does Massimo bring his cat while going to fish with Alberto and Luca? The cat had already been shown to be hostile to the two boys last night and had hurt them.
In Ciao, Alberto, Alberto tries to sneak onto Massimo's boat late at night and is surprised to find that Machiavelli is already on board. It's likely something similar is the case for scenes where he's there in the movie. He's probably meant to be an indoor-outdoor cat who was in the boat before Massimo and the boys boarded it, and by the time they realized, it was too late to bring him back to shore.
Shouldn't Ercole be disqualified?
During the Portorosso Cup Triathlon, why isn't Ercole disqualified for cheating? He force feeds Guido during the pasta eating stage and one kid calls him out for this, but Ercole is nonetheless allowed to participate in the cycling stage.
The whole race is intended to be a fun kid's competition not a professional one. We don't see any judges at the pasta station or along the uphill race route so it seems to be more of an honor system race than one that is stringently judged.
There is a lot of rule-stretching and unjust tactics used throughout all three parts of the triathlon, and not just by Ercole's team.note Ercole covers Ciccio in olive oil to ensure he swims faster than the others, not that it helps. Luca wears a diving suit for the swim race, meaning no one would've been able to see whether he made it all the way to the buoy and back. Giulia teaches Luca how to eat pasta more quickly. Ercole does the aforementioned force-feeding to Guido. Alberto (intentionally or otherwise) uses his sea-monster form to distract some of the other bikers, which helps Luca gain and keep the lead. Ercole kicks one of the other bikers aside and then attempts to kill Luca and Alberto with a harpoon. Giulia sabotages Ercole by ramming him off his bike just before the finish line. And to top things off, the spokeswoman seems to present the victory reward to Luca, Alberto, and Giulia all together, even though Luca had already split from Giulia's team and it's not clear whether Alberto was still on either of their teams. (He didn't participate in the race, at any rate.) All things considered, whatever rules the race does impose on the contestants can't be assumed to be especially stringent ones.
Presumably for the same reason why Ercole is allowed to participate at all over multiple years despite clearly being too old - if he hasn't been disqualified/banned from competing at this point, there's not much else he could do that would get him axed.
It probably helped matters that Ercole ended up not winning. The bystanders and the other racers might've made a stink of things if he'd actually been declared the victor, but the fact he cheated ended up not mattering. The same goes for Luca — the most obvious thing he did that could be considered cheating, wearing the diving suit, hardly gave him any advantage at all since he was still one of the last ones out of the water.
Revealing his true form
In the credits, we learn that after moving in with Giulia and her mother and attending school, Luca revealed his true form to her teacher and classmates. Isn't doing that a bit risky? That the people of Portorosso accepted him and Alberto is one thing, but anyone at school could expose Luca (especially if Luca has met some bully like Ercole) and contact some paranormal hunter to capture him...
One of the less other morals of the film, besides acceptance, is "it's better to be yourself than to hide indefinitely, always living in fear". Ultimately if you take a step back, one can easily also argue why go to school in the first place, as it's inherently more risky than just remaining under the sea, and no amount of rationalization can really provide an airtight reason for Luca's safety. Luca's grandma states "He seems to know how to find the good ones" regarding people that will accept him.
Consider also the "small town conservative people hesitant to accept new things" trope. Genoa is a larger city that likely wouldn't lapse into that kind of hysteria.
Shouldn't Alberto learn how to wind pasta?
Why didn't Giulia teach Alberto to wind pasta around his fork before Massimo got around to it? It's one of the most basic things when it comes to eating pasta; she even taught it to Luca as soon as she saw him struggling.
The most likely answer is that we see Alberto wrestling with New Friend Envy so Giulia probably did try to show him but Alberto just brushed her off. It wasn't until Massimo showed him how to work a fork did Alberto take to it and the story had showed he was bonding with Massimo at that point and was willing to take his advice.
Spewlia?
Why does Alberto initially call Giulia "Spewlia", but after she corrects him he resorts to calling her variations of "girl-human" early on? If he had thought that "Spewlia" was meant to be her name, why would he have a problem with calling her "Giulia" in the same vein? Did he know that "Spewlia" was meant as an insult?
Alberto seemed to originally think her name was indeed "Spewlia" at first. Alberto has shown to dislike being corrected even when he's clearly wrong about something, and Giulia corrects him very adamantly that her name isn't "Spewlia" with no room for misunderstanding, so him calling her "girl-human" might have just been him being a little put upon when trying to correct himself. Later on, he calls her by her name just fine, so it seems that calling her a "girl-human" was more because he genuinely didn't remember her real name.
that was once common but has been in decline. It's close enough to Italian that it's understandable, but naturally there will always be misunderstandings. The sea monsters likely speak an old version of Ligurian, and since many were averse to visiting the surface, they don't go up on land enough to learn how words change. "Stupido", in its old form, meant 'amazed or stunned'. Alberto and Luca probably thought 'What's wrong with you, stupido?' means something like 'What's up, hotshot?'.