The title card starts off seemingly as glowing letters on a stone slab, as befitting the title card of a fantasy film, but as the title zooms in, Tron Lines are seen on the letters, giving it a science fiction feel. This captures the spirit of the film as it starts off as a fantasy film, then adds in sci-fi elements, becoming a mash-up of fantasy and sci-fi.
The title also appears as Thor brings Surtur's skull to Asgard, one of the major events that causes Ragnarok to occur. Thus, the title prophecizes what will happen by Thor's action.
It would make sense that Odin would be found on Norway, considering that this is where he hid the Tesseract long ago and where the Asgardians were worshipped as gods.
As mentioned in Avengers: Age of Ultron, alcohol doesn't affect Asgardians nearly as strongly as it does Midgardians. Thor is shown to be a moderate drinker, but never shows any signs of intoxication-induced impairment. In Valkyrie's first scene, she's so drunk that she can't even make the walk down her ship's ramp without tumbling off the side. Imagine how much she must drink to be that shit-faced. It seems understandable, though, considering she's drowning her sorrows as the result of some extremely traumatic events, namely losing all of her Valkyrior sisters to an onslaught by Hela.
The involvement of Doctor Strange, as per the Stinger in his own movie. It makes sense that Strange would be worried that Loki is here on Earth, specifically New York City. The last time this happened, Loki not only caused a wormhole to appear in the sky (something that obviously would have disrupted the boundaries of the Multiverse, especially given how he used not one but two Infinity Stones), but caused many deaths and injuries. Strange, being a former surgeon at a New York hospital, would have not only seen these events firsthand, but likely treated many of Loki's victims (this is confirmed in Avengers: Endgame). This also impacts the ways he treats Thor and Loki; Thor, while weirded out, is at least received (relatively) politely as a guest, while Loki is caught in a space-portal loop specifically as a security precaution.
Thor considering the Avengers a job makes sense when you consider that, in general, what he was doing before the movies was all part and parcel of his position as a prince of Asgard, something automatically expected of him. Being part of the Avengers was something apart from what would have been his usual routine. Considering he was wearing normal human clothes at some points in Age of Ultron, he probably was given money for essentials as well as room and board in Avengers Tower. Now think about it; barracks to sleep in alongside those you work with, meals, and money for essentials and some personal spending, that's probably what it would look like to serve as a city guard or something similar, given that Asgardian culture seems to echo traditional Norse culture in some respects. Add to that the fact that the Avengers literally protect and guard Earth, it's perfectly reasonable to think that Thor considers the whole thing to essentially be a job where he and his friends work as guards for the planet, which is a totally accurate description of what the Avengers are, anyways.
The Norwegian cliff where Odin tells Thor and Loki to "remember this place" becomes a brilliant place for Thor and Odin's spirit to have a talk about who he's the God of. Why? Think about this: The weather there is overcast and cloudy. What occurs when the skies are stormy enough? Thunder. What makes it more brilliant, Odin chose that spot as a way of foreshadowing that the destruction of Asgard would lead its people to immigrate to Earth. Becomes Fridge-Heartwarming when it occurs that Thor chose Earth so he could be spiritually closer to his father.
It seems a bit flimsy for Thor to first tell Hulk that he prefers him over Banner, and then later tell Banner he prefers him over the Hulk. Until you remember that when Hulk refused to join forces with him, Thor took it back and admitted people on Earth DID hate him. In a way, he was acknowledging he preferred Banner over Hulk, long before he even told Banner those words.
The bright color pallet and use of classic rock in the trailer makes sense when you consider that the film primarily takes place on the cosmic side of the Marvel Cinematic Universe, which seems to be firmly rooted in the iconography of the 1970's and 80's. These are the years in which the Marvel Cosmic Universe began to come to prominence and when Led Zeppelin and others made their mark.
Let's look again at the spell over Mjölnir: "Whosoever wields this hammer, if he be worthy, shall possess the power of Thor." Nothing about it says that the power has to come from the hammer, just that the person shall possess the power. The entire reveal of Mjölnir's true nature was foreshadowed waaaay back in the first Thor film. The line Possess the power of Thor actually meant that the power itself was Thor's and not from Mjölnir, not to mention the little fact that Hela caught the hammer mid-flight. It's because just like Vision, she was worthy of being the hammer's owner, since it belonged to her before Thor was born. Also, neither could use the lightning power of Thor because it was never the hammer that gave him the power!
When Thor and Loki meet Hela, Loki attempts to talk their way out of the situation, and Hela remarks that he sounds like Odin. Even though he's adopted, he's picked up some of his father's manners, proving Nurture over Nature.
In addition, he's trying to talk his way out of a fight (not unwise) which she compares to how she saw Odin during the end of their time together, craven and cowardly.
Thor's banishment as part of Odin's Secret Test of Character in the first movie gets new context in light of the events of this film. Odin already had one warmongering Blood Knight child, Hela, and didn't want Thor to go down the same path. Likewise, it shows in how Loki became a charmer who likes making deals; he wanted a diplomatic son instead of a conqueror. In fact, one can see both sons as Odin's My Greatest Second Chance; one strong warrior son to "be ready for war" and one cunning diplomat son who would "not seek out war". Unfortunately, this turned into a similar mess.
Thor's vision in Age of Ultron makes so much sense now from the lightning coming from within Thor to Heimdall proclaiming that Thor will lead Asgard to its doom.
Loki did the same thing to Odin that Odin did to Thor in the first movie — banished to Earth.
The fate of the Asgardians at the end of the film is a Mythology Gag that references long-time Thor character Beta Ray Bill, who is literally Alien Thor charged protecting his displaced race as they journey through the universe in search of a new home.
Loki at the end:
In the Mid-Credits scene, it could be easily assumed that Loki is up to his old tricks again; it's subtly implied that he took the Tesseract from Asgard, and further confirmed when Thanos's ship shows up. So he's working with Thanos again, right? Doubtful. Ignoring the fact that if Loki really was still working with Thanos then he would've given him the Tesseract earlier (when he was posing as Odin), think about it from Loki's point of view. The last time he had any kind of contact with Thanos (the Other), he was told that his punishment for failure would be unimaginable pain. For all he knows, Thanos is out there looking for him, ready to enact that pain. So he has a choice: he can either leave the Tesseract on Asgard (it probably won't be destroyed, since it's a freaking Infinity Stone) and get caught by Thanos without it and punished by him (and those around him would undoubtedly be hurt as well), or he can take it with him should Thanos show up and use it as a bargaining chip for his safety (and the safety of everyone else). With that choice, anyone with survival instincts would choose the latter option.
If one subscribes to the theory that Loki is actively working against Thanos, then it's only natural he'd bring the Tesseract with him. If he'd left it, it would now be floating among the pile of rubble that used to be Asgard, waiting for anyone to scoop it up.
This has basically been confirmed in Infinity War.
Odin and his sons:
The existence of Hela also gives more insight into the dynamics between Odin and his two sons. Loki keeps reminding Odin, perhaps subconsciously, of Hela's worst traits. His ambition and cruelty, even the way he favours green and styles his helmet are all evocative of his banished sister. Thor, on the other hand, loves battle but is also compassionate and good-natured. Loki reminds Odin that he failed; Thor makes him believe that he has a second chance.
It's also plausible that Loki reminded Odin of himself, seeing as he used to be every bit as vicious as his daughter was.
Also Loki does look similar to and has a similar color scheme to Hela, making Thor look like the adopted one next to those two, which is why Hela commented that Thor didn't look like Odin.
And given that Loki's Human Alien appearance is something imposed upon his inborn frost giant appearance, the fact that he looks so much like Hela suggests that Frigga - the one who taught Loki how to create illusions in the first place - deliberately gave her adoptive son an appearance resembling the daughter she'd lost.
Then we have the events of the first Thor film. Given Hela became an insane Blood Knight conquering despot, it makes sense that Odin would try to squelch any similar tendencies in Thor, which is exactly what the entire first film was all about.
Odin's attitude in Thor: The Dark World after the attack by the Dark Elves is given new light in this movie. It was likely Frigga herself that was responsible for eventually turning Odin away from simply being a conquerer into an actual ruler, and her death caused him to start slipping back into old habits.
Previously, Thor stated that whoever can lift the hammer may rule Asgard. Although it seems like a fairly blase comment from him, Hela proves his exact wording to be true by holding his hammer by force (instead of being proven worthy). Come the rest of the film, we see that she actually is capable of ruling Asgard exactly as stated, but in such a way that it no longer is the Asgard as it was meant to be.
The repeated use of Led Zeppelin's "The Immigrant Song" in the film makes perfect sense in the ending. Not only the Asgardians become exactly that, but also the lyrics say "...Will drive our ships to new lands"
Also, during the big fight scene, "Valhalla, I am coming" plays right as the camera cuts to Valkyrie striding up to the bad guys and beating them up. They really grabbed every bit of applicability they could get out of that song.
Loki on Earth:
During Thor and Loki's short visit to New York, two citizens asked Thor to take a groupie with them while Loki is largely ignored. This could mean that Loki is Easily Forgiven, but he could also either be being snubbed because those two New Yorkers are likely still pissed about what he did during The Avengers (2012) or they're scared to call out a Physical God. Also worth mentioning is that the only person who addresses the issue with Loki is capable of defending himself.
Or it could simply be a case of no one recognizing him without his horns and flashy outfit. He's now just a tall young man in a nice suit, with unusual hair.
Loki probably gets away with Clark Kenting for the exact same reason that the trope namer gets away with it — because he has never given average citizens a reason to believe that he spends any time whatsoever walking around dressed like a human. The fact that Thor lives on Earth part time is common knowledge within the MCU, but the idea that Loki ever would in a post-Avengers world sounds (comparatively) ridiculous. If you lived in this universe and tried to convince your friends that the man in a plain suit standing on the sidewalk next to you was actually Loki, they would probably laugh at you and tell you to be realistic.
In addition, the only time the public gets a good look at him is briefly in Germany. That finishes up in about 5 minutes, he's on the Helicarrier for a while, then after that either Stark Tower or zipping around on a Chitauri ship. He shows up (briefly) in Central Park after that. That isn't a lot of time for the people to see what he looks like, people are more likely to be distracted than taking pictures, it was five years ago, and cellphone cameras in 2012 were grainier and slower than now. There is a high possibility that no citizen knows what he looks like.
Another possibility is that no one on Earth knows those two events are related. It's a long way from Germany to New York, and Germany wouldn't be in a hurry to admit that valuable nuclear supplies were stolen, even if there were more than a handful of people who would realize that those materials were used in the construction of the portal. Without an obvious, public connection between the two (and we established that few if any people actually saw Loki in person in New York) it wouldn't be difficult for SHIELD to suppress any news of a connection between the two. Loki might be more easily recognized in Germany than in New York.
Loki also has the power of illusions too, so it is possible that he has cast some type of illusion on himself, so only Thor recognizes him; Doctor Strange, being a Master Of The Mystic Arts, would likely have the power to see through any illusion, cast by Loki?
Actually, Loki wearing an illusion would be a very good reason for Doctor Strange to respond so quickly to them arriving on earth. Walking around with a powerful spell in an area that used to be home to the most powerful god in all of creation would set off a bunch of alarm bells.
Not to mention the fact that the idea of getting a selfie with Thor would give any fan tunnel vision.
There's also the fact that Loki isn't doing anything, and Thor is just chatting with him. Even if Loki was caught on camera once or twice, people would assume that Thor would attack this supervillain on sight. Since Thor clearly isn't doing anything of the sort, he's not Loki, just a lookalike.
Hulk's comparison of himself and Thor to fire and water despite being the "same" isn't his misunderstanding, both are primal forces, difficult to control, but necessary for life. Furthermore, Hulk is exactly right. Hulk is constantly angry, and like fire for the most part can be directed but never controlled. Thor is just as powerful - arguably more so (after all, water puts out fire) - but has power of a different kind. Rather than the raw destructive power of fire, water is often outwardly peaceful but also unrelenting and capable of enormous feats both destructive and constructive. And by the end of the movie, so is Thor.
Thor easily defeats Surtur at the start, when he has been dying for a long time and is "like smoldering fire". When he gets resurrected and "like raging fire", only Hulk and Hela can land any blow on him.
Related, when Surtur narrates how he will become as big as a MOUNTAIN!, not a house. He bursts out of the mountain-sized building that is the Asgardian palace.
So, why did Heimdall run off? Odin realized he was dying, and contacted Heimdall with instructions, the same way Thor contacted him. If he had stayed at his post, Hela would've targeted him, killed him, and been well on her way to conquering the Realms by the time Thor got back. There's no way Heimdall would hand over the sword willingly. Also, Heimdall being branded a traitor as Skurge said may have just been a political ploy by Loki to discredit and drive off the one person who could see through his deception.
Or perhaps Loki was thinking about the time that Heimdall committed treason in Thor 2note when he aided Thor's escape against Odin's express orders... or the time he committed treason in Thor 1note when he sent Thor and company to Jotunheim knowing full well he would stir up an incident, again against Odin's wishes, and also the time he stood against Loki who was, for all his instability, the legitimate regent. And in this movie, he commits treason again. Hela IS a rightful heir, being firstborn, so opposing her is treason.
Skurge said Odin labeled Heimdall a traitor, but the movie never clarified which Odin. It could have been the real Odin before Loki replaced him, and Loki just never bothered to reverse the decision. It makes some sense when you consider the last face-to-face interaction between Odin and Heimdall was of Heimdall announcing his own acts of treason and drawing his sword as if to strike his king back during the events of Dark World.
Thor's statement about Sokovia blowing up two years previously means that Banner has been "asleep" for two years... but only on Earth. We learn that time flows differently on Sakaar so Hulk was likely in charge for several years. The time flowing differently on Sakaar could also explain why Valkyrie still looks roughly the same age as Thor and Loki, despite being older than them.
Not only does time flow differently on Sakaar, but the Grandmaster reveals that anywhere else, he'd be millions of years old. This implies that not only does time operate out of sync with the rest of the universe, but nobody on Sakaar ages or can die of natural causes. This makes the chaotic, lawless, and violent nature of the world much more logical. As without the roving murder gangs and blood sports, Sakaar would have a massive overpopulation problem almost immediately. Even with such measures, food seems scarce because the gang that tries to capture Thor, and presumably have captured other newcomers, are looking to eat him.
Despite being from the race that originated Norse myths, Thor often says things like "What the Hell?". This might seem like just a case of suspension of disbelief, but with the revelations of this film it makes much more sense. Before Odin covered it all up, Hela would have been a name that struck fear into the hearts of every being in the universe. Maybe some of that influence lingered even after she was gone. Alternatively, he could have been spelling it "Hel" all this time.
Either that, or he's been hanging around with slang-using Deadpan Snarker-types like Stark and Romanoff too much on Earth, and picked up a lot more of the lingo.
One of the first statements out of Thor's mouth in this movie is "Surtur, son of - a bitch!" According to the other site the etymology is: Alteration of an earlier phrase represented by Middle English biche-sone ("son of a bitch", literally "bitch's son"), Old Norse bikkju-sonr ("son of a bitch").
By the end of the movie, Loki has repaired his relationship with Thor and redeemed himself, opting to help save the Asgardians from Hela's wrath. What is it that motivates that? The only thing that ever motives Loki to do anything: To spite his brother. To explain; Loki is ready to betray Thor again while in Sakaar, but Thor, having just finished explaining how he's accepted that Loki isn't his brother any more, predicts Loki's move and stops him, giving him a disappointed speech about how Loki has became predictable and will probably never change his ways. Loki decides to help stop Hela, fix his relationship with Thor, and save their people, all to prove Thor wrong. It's also a fun Mythology Gag for anyone who's followed Loki's contemporary developments in the comics, as besides proving Thor wrong, Loki wanted to change his ways because he became predictable. That's exactly what motivated Loki in the comics to pull his reincarnation gambit that lead to him evolving into a more heroic character; he wanted to avoid being predictable and escape the role the world had made for him.
This movie further justifies the "convenient Odinsleep" back in Thor: The Dark World. Not only did Odin use his life force to send Thor back to Earth during The Avengers (2012), he's also been using it to keep Hela banished in her dimension. It's a real miracle he survived this long.
Of course, Hela would dismiss the Infinity Gauntlet in the vault as fake. Not only is it adorned by typical jewels instead of the Infinity Stones, it's also the wrong hand.
Heimdall's job throughout the movies is basically to watch over a bridge. At the end of the movie, he also did that, albeit a different kind of bridge. Specifically, a spaceship's bridge.
For someone who can see through all nine realms, Heimdall didn't see the large wolf at the other end of Bifröst. Well, not only he has to do it actively, but what he sees is souls, something the reanimated Fenris wouldn't have.
Hulk is better at verbalizing and holding conversations in this film then we've ever seen him be before. That makes sense considering that not only has he just experienced his single longest period of being the dominant personality inside Banner, he has also been given a regular social companion in Valkyrie. Sakaar has finally given Hulk both the motivation to develop some social skills as well as the time required for him to actually learn them.
This is also a plausible explanation for how he was able to remain the Hulk for so long. We know from the first Avengers movie that Banner learned to control the Hulk with his own anger; stands to reason that the Hulk could learn to control Banner with his own humanity.
During their conversation in the Hulk's quarters, Thor manages to lift the control to the shock disk out of Valkyrie's pocket. Where did a Prince of Asgard learn to pick pockets? Probably from Loki. (Or Widow. Or Hawkeye. Or maybe even Cap.) It also doubles as unusually sly for Thor: he never really expected to be able to convince Valkyrie to help him, he just wanted to get her within arm's reach.
Hela picks up some fire from the Eternal Flame and takes it down to the crypt to revive her army, but Loki brings Surtur's crown to the Eternal Flame. Of course he does. As a Jotun, he probably doesn't mix well with unyielding fire.
As is pointed out below, Odin built Asgard through conquest and death. What is another way to phrase that? Fire and the sword. Odin stoked Hela's bloodlust and need for conquest, then locked her away when it grew too much. Without Hela, Thor would have never allowed Surtur to destroy Asgard. How did Surtur destroy Asgard? Fire and the sword.
If the wormholes around Sakaar are a natural phenomenon, then its status as a Landfill Beyond the Stars makes sense — advanced spacefaring civilizations would use the portals to safely dispose of their trash.
During the scene where Thor and Loki attempt to steal the Grandmaster's luxury craft, the scene shows Loki making an illusion of himself to walk alongside Thor, while his real self is walking to a control panel on the other side to alert the guards. Given that every time Loki uses his illusions before this scene, we've never seen it coming. The fact that we can clearly see that Loki is up to no good this time around foreshadows the scene just after that where Thor reveals that he knew and didn't fall for Loki's trick this time: Loki's getting so predictable that even us, the audience, can see his betrayal coming.
In sharp contrast to the Embarrassing Nickname Tony programmed the Quinjet to recognize Thor as, Bruce Banner is referred to by his real name and also as the "Strongest Avenger." Considering that the two are memetically Science Bros.and the Hulk saved his life in the New York invasion, it makes sense that Tony would be complimentary to both.
There is also some Brilliance in the Embarrassing Nickname. Tony has always been concerned that his tech would wind up in the wrong hands, so when he programs the access codes he makes sure they are words and phrases only other Avengers would know and wouldn't be known to the public. Most people would guess the voice access would respond to "Thor Odinson" or something similar, not "Point Break".
There's also a bit logic to Thor's password being a seeming insult - Thor can fly. Tony likely figured there'd never be a need for Thor to try and pilot a Quinjet, nor would he expect Thor to know how to pilot it. The password was there, but Tony never intended it to be used.
Doctor Strange easily handles both Thor and Loki, moving quickly to counter every single thing they do with no mistakes on his part—quite a departure from his many fumbles in his own movie. While he's certainly learned a lot since then, he's also wearing the Eye of Agomatto at the time. It's quite possible he made plenty of mistakes, but rewound a few seconds to fix them.
How did Strange incapacitate Loki and keep Thor off-balance while he questioned him? Opening portals via sling-ring and blinking from location to location inside his Sanctum. Where did he get the idea that sudden, unpredictable portals were something that Asgardians might be put at a disadvantage by? Probably from associates at the London Sanctum, who'd looked into the events of Thor: The Dark World once that crisis was over and realized that both Thor and Mjolnir had been seriously inconvenienced by all those naturally-occurring random portals.
Hela remarking that Loki sounds like Odin takes on a new meaning when you remember that the both of them tried to edit the past in order to make themselves look more benevolent. Odin literally covered up what he had to do to achieve Asgard's glory while Loki commissioned a play where he died an absolute hero.
A second interpretation is that Loki also sounded manipulative, which Odin gradually became as the years of war gave way to peace. Silver tongued and all that, always measuring your words carefully so you don't say the wrong thing or for the maximum benefit.
Yet another way of looking at it: the last Hela knew of Odin, he decided he no longer wanted to (primarily) use force to get what he wanted; the implication then is that he had to make agreements and compromises with people (the peace treaty with Laufey, for example). What does Loki say to her when they meet? "Perhaps we can come to an arrangement?"
When Loki's projection visits Thor in the gladiator cell, the last thing he tells him is that he placed a large bet against Thor. Seems a bit cold, considering Loki's later more amiable relationship with Thor after the escape? But consider that those words did enrage Thor and had the champion been anyone else besides Hulk, Thor might've channeled that rage into even greater strength and determination. Being an illusionist and mind-bender, Loki was using psychological manipulation to motivate Thor.
Thor's Deadpan SnarkerCasual Danger Dialog while bound in chains before Surtur can seem grossly out of character for someone who was never particularly quippy before. But it makes a lot of sense if you view it as Thor deliberately trying to wind up Surtur so he'd give the details of his role in Ragnarok during his Evil Gloating speech. This also shows Character Development on part of Thor that he would use psychology and talking at such a degree instead of just force.
Three guesses which Avenger he may have gotten the idea from, and any guesses that don't look like Scarlett Johansson don't count.
Loki/Odin having exiled Sif from Asgard, explanation perWord of God, becomes understandable, as since most everything Loki learned and is capable of doing has been primarily from Frigga more than anyone else, he would have a genuine appreciation of women's intelligence and intuition. So Loki would believe that Sif would be the one most likely to notice something off about "Odin", which he figured that the Warriors Three and even Thor would not.
In first Thor movie we hear Odin say that Mjölnir is great tool for both destruction and creation. Yet we haven't seen it do much creation in Thor's hands, unless you count the birth of Vision, but that may have been simple electric overload. And what creation could a lightning hammer do anyway? However, once we learn that a) it was a tool to let a gifted Asgardian learn how to focus their powers and b) Hela had it, its probably safe to assume she learned to create her swords with it, hence the powers of creation.
What was the name of the play that Loki commissioned to celebrate himself? The Tragedy of Loki of Asgard. As any High School English teacher can tell you, the defining characteristic of a tragedy is a central character (Rarely a commoner, almost always nobility or royalty of some sort. Or even a god.) undone by his own flaws. This could mean Loki was finally beginning to take responsibility for his own actions and misdeeds, enough to acknowledge them in his play. A nice foreshadowing of his redemption arc later in the story.
Another, slightly more obvious and Heartwarming in Hindsight bit of Foreshadowing from that play. While Thor and Odin's characters come across as a bit goofy and hammy, nothing about their portrayal is actually unflattering or condemning of their actions either. Even before his HeelFace Turn, Loki did care about his father and brother despite their antagonism towards them.
In the first Thor film, Thor walked into a pet store demanding a cat or a dog that was "large enough to ride". In this film, we see that he wasn't kidding; Fenris is a kind of dog, and he is definitely large enough to ride.
Where did Thor get all his guile and trickery from after losing Mjolnir? Well, he did hang out with Loki for most of his life and Black Widow for the past few years. Also, he's a prince. This sort of thing is really standard training for royalty, he just didn't need to use it.
When Thor is telling the story of Loki turning into a snake to stab him he says something interesting. "We were eight at the time." We were eight, not "he was eight" or "I was eight". As in Loki and Thor are relatively the same age. Adopted or not, they were raised as twins.
In fact, them being raised as twins explains a lot about their personalities and their history. How did Frigga hide the fact that she mysteriously had another child? Simple, claim that Loki was an unexpected twin, swear the doctors to secrecy, and bam! New kid, without the hassle of pretending that she was pregnant again. Why is Loki so obsessed with getting the throne? Because he thought for the longest time that he was only a few minutes from being the firstborn, and the heir.
Hela is black-haired and not as built as Odin or Thor, which gives a good explanation for why Loki was able to get away with being Odin's son for so long without anyone questioning why he didn't look like his brother. Hela proves that someone of Odin's descent can actually look like Loki.
Additionally, Loki's Asgardian form could have been modeled after Hela.
As it has been established, Thor was holding back on his own power while using Mjolnir. However, it doesn't just extend to Hela and Thor. It extends to the franchise itself along with Chris Hemsworth's performance. After all, once Mjolnir is destroyed, Chris is allowed to bring in his full potential as a comedic character, and the Thor movie series is saved.
Laufey's hatred of Odin in the first movie makes even more sense now: not only did Odin thwart his attempted conquest of Earth and steal the Casket of Ancient Winters, Odin was acting as the wise, moral law-enforcer of the Nine Realms when the only reason he had the power to do so was because in his youth he'd succeeded at exactly what Laufey tried and failed to do. It wasn't just the defeat, but the hypocrisy.
Surtur's line that he is Asgard's doom and so is Thor could be because by leaving Asgard defenseless, he is a cause of Asgard's destruction, but it could also be foreshadowing Thor causing Ragnarok himself. It's possible that the prophecy is that Thor and Surtur destroy Asgard but not how specifically. It's also possible that that prophecy states that Thor will destroy Asgard using Surtur.
Hulk's dismissing Thor's lamenting his loss of Mjolnir and his father as whining may not just be him being petulant. For one, Hulk thinks Mjolnir is not important because Thor has proven during their fight in the arena that he doesn't need Mjolnir. To the Hulk, it looks like Thor is whining about losing his favorite toy. This is also foreshadowing that Thor doesn't need Mjolnir. For two, Banner doesn't have a good relationship with his father and in a deleted scene, Banner reveals he missed his own father's funeral. So Hulk may be acting on Banner's memories subconsciously and dismiss losing a father as no big deal. So to the Hulk, it looks like Thor is whining about unimportant things.
Loki snarks that "open communication was never [their] family's forte", whereupon Thor answers "You have no idea, I've had quite the revelation since we spoke last." Last time they spoke was when they argued in the dungeons. And after that, Thor had the "revelation" that trying to handle Loki like he used to in the past ("open communication") would eventually lead nowhere and he would have to use other means to get through to Loki: Trickery and reverse psychology.
Hulk's reasons for trying to stop Thor from leaving become more apparent when Banner starts talking about The Devil's Anus and starts explaining exactly what it is and how dangerous it is. Seems he had more control over The Hulk than he thought.
Alternately, Banner's massive intellect doesn't just disappear when he's transformed, Hulk, generally, is just too angry to use it in the same way, or it's channeled into a different outlet, but it's still there.
Why are people so accepting of Loki coming to rescue them in the end? Well, look at the the timeline of events of things Loki has done from an Asgardian commoner's point of view:
Loki is publicly known as the God of Mischief and a trickster, which means he has a certain reputation. However, he is never referred to as the God of Lies or the God of Evil, which means that to the populace, he might have been viewed as the prankster of the Asgardian royal family compared to Thor's hard-drinking war-bro image. And everyone likes jokesters.
After Thor and his friends run off to Jotunheim in a hot-headed way that would have instantly pegged it as Thor's idea, Thor is banished, leaving Loki as the sole heir. If the guard Loki had commanded to inform Odin had spread gossip, all anyone would know was that Loki warned his father that Thor was off to do something really stupid.
Odin falls into the Odinsleep. Only he and Loki are in the treasure room for that discussion, and when Loki calls for the guards, all they see is the clearly distraught prince cradling his unconscious father, which is exactly what it is. He then takes the throne, because he IS the heir, and it's unknown if or when Odin will wake, and as heir either way he's in charge and needs to run things. Thor's friends request he end Thor's banishment, and he gives the perfectly reasonable explanation, in front of guards as witnesses, that his first act while in charge can't be to countermand the king's orders. He then secretly plots with Laufey, but no one knows he does this, and only Heimdall suspects.
When Thor's friends, who enabled him in going to Jotunheim to make trouble, use the Bifrost to go to Earth, Loki apparently sends the Destroyer after him. After all, they're known troublemakers going to meet with exiled royalty, and ignoring that is just asking for a coup and civil war. He can't send a force of guards large enough to subdue the warriors and Sif, because that would look like an invasion force and an act of war. The Destroyer is powerful enough to stand against them by itself and bring them back if need be, enough to count as only a police action. No one on Asgard knows it has orders to kill.
Laufey "breaks into the palace" to kill Odin, but Loki kills him, protecting his father, in front of his mother no less, the parent he's actually close to. Justifiably pissed off, he goes and plans to use the Bifrost to destroy Jotunheim for the attempt on his father and endangering his mother. Only Heimdall would know Loki let them in, and it would be his word against the heir, that the giants didn't manage to get in when he was negligently away from his post and the Warriors Three and Sif managed to get to Earth.
The Bifrost explodes, and Loki apparently falls to his death. Unless Thor and Odin allowed the dirty details to be made public, Loki doesn't look anything but a dutiful son and hero who gave his life trying to bring justice to the Jotuns.
After the events of the Avengers, Loki is alive, and dragged back before the throne in chains. Unless the specifics were made public, all anyone would have to go on is the conversation before the throne where Loki mocks Odin, a year after he's been brought to Asgard. All anyone would see is that while he was 'away', Loki did something on Earth that really pissed Odin off, and he's been imprisoned for a year so far. Given Asgardian lifespans, that's being made to stand in the corner for being naughty. Note that this is in comparison to Thor invading Jotunheim, which got him banished. Since Loki is still on Asgard, it must look like a comparatively light punishment for a smaller offense, especially given Odin's preference to either cover things up or cast it out. Loki looks to be getting off easy.
The Dark Elves attack, and come in through the prisons. Unlike other prisoners, Loki stays put, looking very law-abiding. The guards who'd later come down to put all the prisoners back would be able to gossip about this. Given his cell has glass walls, his tantrum upon hearing of the death of his mother would have been very public and very filial.
Thor breaks him out of prison to get revenge on the elves despite Odin's orders not to leave Asgard, something Thor has done very recently and been banished for. Odin sends guards after them, which they evade, and they go off to Svartalfheim, where Loki apparently dies for good (again). The only details about how are from Thor who (considering Loki's sacrifice to save Jane and avenge their mother) would give events a good spin. These details are the basis for the play The Tragedy of Loki of Asgard, which makes him look even better and would be more available to the public.
Years later, Odin has been Loki all his time, which is exactly the sort of joke that people might expect from Loki given how he once turned Thor into a frog, and Thor immediately drags Loki off to Earth to find Odin. Neither prince returns, having apparently been killed by Hela.
Then in Asgard's darkest hour, Loki shows up with a ship to get everyone out of Asgard and away from Hela. He then fights the undead warriors to buy the civilians time to board and escape.
Unless Odin aired a lot of dirty details that only he, Thor, and the audience were privy to (which seems highly unlikely since he preferred cover-ups), no one knows the full extent of Loki's actions, and given the publicly available facts, it's actually very easy to come to the conclusion that the jokester younger prince, after his father fell to the Odinsleep, Took a Level in Badass by taking charge of the realm, acted to enforce Odin's last command, tried to get revenge for an attempted assassination of the king, did some unspecified mischief on Earth where he was only lightly punished, avenged the death of his mother, pulled a prank involving impersonating Odin, apparently died again, then arrived at the last minute to save them all with a ship and warriors to protect them while they boarded. Given all that, the Asgardian civilians thinking well of Loki is completely justified.
It has been said that the most believable lies are permeated with truth. Loki, the God of Lies, would know this, and this would definitely coincide with the above.
A very related meta trivia here: in summary, we see an heir who, despite his reputation for being unpromising-yet-of good cheer shows his mettle when the right time arrived. Did this exist in fiction before? As it so happens, yes: this was the very character arc William Shakespeare did for his fictional Henry V, as was shown in Henry IV. It is also perhaps fortuitous coincidence that Tom Hiddleston was doing this very same role in The Hollow Crown—and the thematic overlaps of both are something he acknowledged himself.
Post Infinity War, the scene where Bruce faceplants into the Rainbow Bridge is not only a Funny Moment, but actually makes sense. Word of God (Joe Russo on the DVD Commentary) states that Hulk's refusal to come out when Banner wants him to doesn't stem from the fact that Hulk is scared of Thanos, but because he's simply tired of being asked to come out only for major battles and then revert back to normal after the crisis has been averted. That means that the reason Banner failed to transform into the Hulk here wasn't because he couldn't change fast enough, but because Hulk was preventing him from doing so. However, Hulk has to participate in the fight anyways to make sure Bruce doesn't kill them both by slamming into the bridge.
During the film's climax, Thor draws Hela into a fight by sitting on the throne and beating Odin's spear against the floor. Hela naturally comes to answer his challenge and deal with her troublesome little brother. In doing so, she implicitly recognized Thor's authority by answering his summons, affirming that Thor was finally ready to accept his responsibilities as the rightful heir after their fathers' death.
Thor heard about electronic mail but isn't aware why he needs a computer for them. As the God of Thunder, he probably believes that he can send them by his own lightning power.
Meta: Why did they cut off Thor's hair in this film? Well, in practically the next scene, Thor starts using his lightning powers for the first time without Mjolnir's help. If Thor still had his long hair, the filmmakers would have had to have shown it sticking out everywhere due to static electricity whenever he used his lightning powers!
The short exchange between Loki and Heimdall on the Rainbow Bridge makes much more sense if one remembers that as shown in Thor, Loki can hide himself from Heimdall's sight whenever he wishes to. Heimdall "saw him coming" because Loki wanted to be seen and allowed it, hence his reply "of course you did."
Bruce complains about Tony's pants being too tight (recall that Tony's clothes were all Thor could find in the Quinjet for the newly de-hulked Bruce to wear). It's worth noting that for the past few movies, he's intentionally been wearing stretchy pants so he wouldn't ruin them hulking out. Even assuming Tony didn't like wearing skin-tight pants to show off the goods, non-stretchy fabric would be weird for Bruce to get used to.
At one point, the Grandmaster is having a conversation and mentions that Scrapper 142, always finds and brings him the best fighters and contenders for his arena. Of course she does. She is a Valkyrie, that is their whole job description, and she used to be a warrior.
A bit of fridge humor. What got Korg arrested? He didn't print enough pamplets for his revolution. In other words, Paper beats rock.
And in the climax Korg thinks he has killed Miek by stepping on him. Miek has "knives for hands". Korg thought scissors was beaten by rock.
If Ragnarok plays how like the mythological Ragnarok plays and Odin knows this, it would make sense he would have Fenris killed because Fenris is fated to kill Odin in Ragnarok. It's possible Fenris tried to kill Odin to free Hela.
In the Japanese dub: Hela is voiced by Amami Yuuki, former top star and otokoyaku (male role actress) of the Takarazuka Revue. Her experience playing men for the Revue gives her a Contralto of Danger that's a dead-ringer for Cate Blanchett's Hela. Additionally, had Thor: Ragnarok been a Takarazuka production, Hela falls perfectly into the kind of female role that would typically be played by otokoyaku as a Cross-Cast Role: villainous, domineering, and sensual (if not sexual). The musumeyaku (female role actress) ideal is a Proper Lady, so they're not often cast as female villains or Femme Fatales. The Takarazuka acting style is considerably more melodramatic than typical western theatre - think of a better-acted version of The Tragedy of Loki of Asgard -, which further qualifies Amami Yuuki for being a Large Ham as Hela.
Aside from catching the receivers of it off guard, the reason "Get help" works is because canonically Loki weighs about 500 lbs. Getting suddenly hit by something that weighs that much would knock out pretty much anything or at least leave them stunned long enough for Thor to finish the job.
When Valkyrie goes to get Thor from the marauders who initially got him but she falls over because of how drunk she is she accidentally falls into a dead being who looks scaly, furry and has big antlers, the exact description that Thor gave of the bilgesnipe to Coulson, in the The Avengers (2012). An amazingly subtle Call-Back.
When Thor first comes into the palace near the end of the movie, before he beckons for Hela to come he takes a look at the broken mural on the ground and there is a specific crack over mural Thor's eye, good foreshadowing for what's going to happen to Thor very soon.
The Hulk has been basically the arena executioner on Sakaar for two years. How many political dissidents and prisoners did he kill along the way? These games seem to take place at regular intervals, and we see the bones of several previous gladiators, and he had to become champion somehow.
Considering that Sakaar works on Narnia Time, it's possible that subjectively, he's been the Hulk for far longer than two years.
In Age of Ultron, Banner was depressed to learn he might have killed a few Hydra goons while fighting as the Hulk. Nobody explicitly told him in this movie what he'd been up to while stuck as the Hulk, but the revelation that he's murdered likely dozens of people for sport won't be a fun moment.
Plenty of Korg's dialogue could imply that fighters don't get forced to fight the champion, but that they choose to challenge him, incentivized by the promise of freedom if they can defeat him. If this is the case, while he's still probably killed more then just a handful of challengers, at least there's a good chance most of his opponents knew exactly what he was capable of and the risks of taking him on.
Add in Korg's line, and the horror mounts:
Korg:[seeing Hulk lining up a fist from low orbit at Thor] Another day, another Doug.
Thor's plan to steal the Quinjet was doomed from the start. It can't maneuver in zero-g, as shown in Agents of S.H.I.E.L.D., and doesn't have the shielding necessary to traverse the Devil's Anus (it's a very fancy fighter plane, but doesn't have anywhere near the shielding the ship they end up stealing does). Basically, Thor would have gotten them all killed if he had succeeded in launching it.
Thor likely doesn't learn that Hela killed Volstagg, Fandral, and Hogun until after the events of the film. After everything he's gone through, he still has to discover and deal with the loss of his closest friends.
Volstagg's daughter is now an orphan, if she survived at all. In fact, since it's likely that most of the warriors of Asgard fought while the noncombatants fled, it's also likely that Thor's ship now consists largely of orphaned children.
Actually, MCU Volstagg has three children. And the original comic book version has around 20. Imagine if the film version followed suit: the odds of him losing some of them are VERY HIGH.
Bruce worries that if he changes to Hulk again, he might never come back. He does and it's unclear whether he is able to change back as only Hulk is seen after that point.
Odin could've asked Heimdall to open a gate, or asked Strange to contact Asgard, but he decided to die quietly instead. Maybe he felt he was unworthy after his mistakes in the last film. Or maybe he was just tired and wanted to join his wife. Considering Hela's imminent return reminded him of the nasty things he had done to get his position as king of the Nine Realms, it could be a case of Redemption Equals Death like The Ancient One accepting death for dabbling in forbidden magic. Or a selfish act where he died rather than accept facing his fatherly screw ups with Hela, leaving his sons holding the bag.
Or, alternatively, he might have chosen to die on Earth instead of return to Asgard in order to prevent Hela from going to Asgard. He knew that his death would unleash her, and if he had died on Asgard, he would have brought her right to its doorstep.
Odin may have tried his best to hide it, but the whole Nine Realms are founded on conquest and death. That's made explicit. The Fridge Horror comes in when you realize that Asgardians aren't the only long-lived race. The Frost Giants, the Dark Elves, and the Fire Demons all remember the early days of Odin's rule or even before. It only makes sense that they hate Asgard. They're not just bent on tearing down the Nine Realms out of spite or For the Evulz, they're returning the favor. And even though now Asgard is dedicated to acting only to maintain the peace, many of their would-be foes are just as old. The Nine Realms have avoided the wars of the rest of the universe because nobody wants to be the one to Awaken the Sleeping Giant.
Hela is a real nasty piece of work, but then you have to realize Odin encouraged it, and she was his chief soldier, his executioner. And his solution was to imprison her for centuries, where she likely went even deeper into her bitterness and rage. Now, remember that he did much the same thing to Thor and Loki when they proved disappointing. Thor just got sent to Earth and had a great time of it, which enhanced his puppy-dog nature while Hela's imprisonment was likely nothing so pleasant. Jane and Darcy may have prevented a bigger disaster than anyone could realize.
Thor says that he loved snakes as a child, which is pretty cute until you remember that in Norse Mythology, he's fated to be killed by one.
It's going to suck for Thor and Bruce once they hit Earth and get caught up to speed on what happened while they were gone. Especially given that Thor is no stranger to dysfunctional family dynamics by now. He's the most likely to start screaming What the Hell, Hero? at both Tony and Steve because if he can forgive Loki's actions, what's their problem? For Bruce's part, he'll discover that his most obsessive enemy is now the United States' Secretary of Defense. It's possible that he would have to choose between being Ross' lapdog or never setting foot in the United States ever again, and we all know that the Other Guy is the soul of diplomacy and obedience. Of course, that's not gonna matter for Thor, because now he has muchbigger problems to deal with.
In the first Thor film, there's horses. When Asgard is evacuated, no horses are seen among the survivors. So, unless Loki decided to set all the horses free on Midgard during his time impersonating Odin, all those horses died during Asgard's destruction (or Hela's reign of terror). It's not just horses either. Thor is familiar with dogs and cats, some of which are "large enough to ride". None of those large ones are seen at the end. Neither are regular sized ones, though they could be hiding under cloaks.
All that remains of the Asgardians at the end of the film in addition to the heroes are a few hundred civilians, maybe around a thousand at most. The entirety of Asgard must have had a significantly higher population than that. This means Hela and her forces slaughtered thousands and thousands of defenseless people offscreen while Thor was stuck on Sakaar, simply because they would not accept her as their new queen.
At the end of the film, Surtur is resurrected and imbued with enough power to grow into the size of a skyscraper and destroy the entirety of Asgard. All of it, including the very earth of it. He might very well have survived this, and remain in that state, unless Thanos finds him and takes care of him.
And who even says he'll do that? A skyscraper-sized behemoth that wants to destroy absolutely everything could be a very powerful ally for someone wanting to take on the Earth's Mightiest Heroes...
Loki's anger towards Strange for his trap is Played for Laughs, but Loki was likely having flashbacks to when he fell from the Bifrost years ago and ended up in Thanos' hands.
What if Thor decided to go for Odin alone, and then return and get Loki out of his captivity when they were all ready to be teleported back to Asgard immediately, to prevent him from further mischief or causing trouble? Remember, at that point Thor was not expecting Odin to die, or that an evil goddess of death would show up. Things looked pretty mundane by then. If he did that, then Odin would have died with just Thor, Hela would have attacked him — and Thor would've most likely died in Norway. The only reason Thor fell to Sakaar and Hela reached Asgard was because Loki told them to open it — Thor even shouted 'NO!' and tried to leap out of its beam — he knew that was a bad idea and was planning on fighting Hela then and there. However, without going through what he does in Sakaar, he would've been killed in battle then and there (because he didn't have The Reveal about his hammer yet), and Hela would've been unopposed... and Loki would be falling and falling and falling, the whole time.
Although this turn of events means that Hela is stuck on Midgard, which sounds good, right Wrong! Hela would find a way back to Asgard no matter who she'd have to kill or how much destruction she'd have to cause. Doctor Strange might have taken care of her, given the way he handily managed Loki and Thor, but Hela might instead steal the Eye of Agamotto from him.
In the mid-credits scene Loki expresses a shocked and disturbed expression while Thor looks rather curious to cautious upon seeing Sanctuary II. Given his experience with Thanos, he likely knows this means very bad news.