At the beginning of The Silver Chair, Caspian is going to find Aslan and ask him what to do about his successor, given that his son and heir has been missing for years. When Jill meets Aslan for the first time, he tells he has been calling her and Eustace since before they called to him, and he then gives her the mission of finding Prince Rilian. Aslan was planning the answer before Caspian had even asked the question!note Given that Aslan is meant to represent Jesus, Lewis may have intended this realization.
When Edmund meets the White Witch, he's very enthusiastic about getting some Turkish Delight from her. Remember that back in England, it's World War II, so everything is rationed and luxury foodstuffs are in short supply. The Pevensies probably haven't had any of their favourite sweets for ages.
In The Lion, the Witch and the Wardrobe, in the scene where the White Witch comes over a group of Narnians having a Christmas party and turns them into stone, the narrative describes how one of the statues still has the fork halfway to his mouth. A few paragraphs earlies, it is described how one of the partygoers — more specifically the father squirrel — is in the middle of eating when the Witch approaches and stops with the fork halfway to his mouth. But the thing is, the Witch doesn't turn the partygoers into stone straight away; she spends what must be over a minute threatening them, and getting the story on how they've been given the feast by Father Christmas. This can mean only one of two things. Either the father squirrel sat there with the fork halfway through his mouth for that entire scene, or someone in the party just looked at the Witch, went "meh," and cheerfully continued eating while she was threatening them all.
That squirrel probably did have that fork in his mouth the entire time. Think about it: the White Queen, has just shown up in the middle of your Christmas party and threatened to kill you and your family. He was probably so scared he didn't think to pull the fork from his mouth.
A talking squirrel is still a squirrel. Squirrels tend to freeze in place, in an instinctive effort to remain unnoticed, when there's a powerful predator nearby and the closest tree is too far to dash to.
The two noblemen who conspire to stab Miraz in the back when he duels Peter had intended to lead the Telmarines to victory, then claim control of the kingdom themselves. But even if they won, Miraz had a legitimate heir: the newborn son whose birth spurred Caspian to flee into exile, in the first place. In other words, they were also planning to murder an innocent baby to secure their claim to power.
Practically most of the fates of the Seven Lords in Dawn Treader.
The fate of Susan in The Last Battle. She's still in our world, but her entire family has died in a violent train accident. She also doesn't get to join her family in Heaven.
Especially horrific as Susan is specifically not going to Narnian heaven because she's become obsessed with "lipstick, nylons, and invitations" and believes Narnia was a game they played as children. It's implied that her lack of faith is the primary reason for her being shut out, but Lucy specifically berates her absent sister for wanting to be a young woman and enjoying things young women were meant to and often pressured to enjoy in the 40s and 50s. Even worse, Susan has already had a chance to be an adult in Narnia, and had it taken away—a twenty-something forced to go back to a teenager's body would probably want to leave it as soon as possible. So Susan gets punished for wanting to be treated like the adult she is, enjoying feminine activities, and trying not to look like a Cloud Cuckoolander. I love Aslan, but he clearly has a very extreme view of what gets you kicked out of heaven.
We don't know that Susan will never find her way back to Narnia; "once a king or queen in Narnia, always a king or queen in Narnia." We just know that she won't get there NOW. She's in the 'real' world a young woman who has just lost her entire family—which is very sad, but such things happen; we don't know if she will recover her childhood faith or not. (Just as Lewis himself became an atheist as a teen, dismissing the Christian faith in which he grew up as foolish stories, but became a Christian again as an adult.)
The other Pevensies saw their parents waving to them from an adjacent area of Heaven, and their parents probably never believed in Narnia in the first place. Our world presumably has its Heavenly counterpart near Narnia's, or perhaps linked to Narnia-Heaven just as our mortal world has links to mortal Narnia. Unless Susan winds up in Hell instead, she'll be able to reunite with her siblings someday.
Susan doesn't get banned from heaven for liking lipsticks and nylons, she just doesn't join her siblings and may end up finding her own way back to Narnia.
It would make it to horror if Susan had been killed and damned, or if her bereavement were the end of her story. But as Lewis notes elsewhere, "Pain insists upon being attended to. God whispers to us in our pleasures, speaks in our consciences, but shouts in our pains. It is his megaphone to rouse a deaf world." God has just done something major that brings some of those He loves (like Lucy) into bliss, and apparently in Lewis's view stands the best chance of getting Susan's attention and bringing her, too, to Paradise.
Also in The Voyage of the Dawn Treader, when the characters reach the end of the world and meet Aslan. Aslan tells them what lies behind him is his country. Reepicheep asks Aslan if he could enter. He accepts and Reepicheep goes to his death. Yeah, Aslan's Country is really heaven, and Reepicheep just killed himself. Even worse was that Caspian wanted to go just to check on his father.
Aslan's tendency to bring young children into Narnia and turn them all into professional killers, something even the White Witch drew the line at!note (Her interactions with Diggory, Polly and later Edmund basically just involve her manipulating them). Edmund in particular demonstrates several signs of being a Shell-Shocked Veteran and he's barely in his teens!
If Aslan is to be taken literally when he says that they are opposites, then Tash may be far worse than Satan. To be truly opposite to Aslan/The Emperor he couldn't be his creation, he'd have to be a being of independent and equal power. Jadis is the rebel Lucifer, Tash sounds more like some kind of Anti-God.
Calormen is based on how the ancient Middle East appeared in British popular fiction; what was the religion of ancient Persia? Zoroastrianism, which does teach the existence of such a being (Ahiriman, the Lord of the Lie).
I don't remember Aslan ever claiming that Tash was equivalent in power to The Emperor, only that Tash and Aslan are moral opposites.
Jadis was waiting in the Hall of Images for long enough for the sun to turn into a red giant, yet the city hasn't been ground into dust by earthquakes or volcanic activity... because there isn't any. She didn't just kill all life in the planet. She killed the world itself.
No, she didn't. A significant point in her interaction with Polly and Digory comes from her not understanding what Polly means when she says that the sun looked funny. She then casually remarks that the sun has looked like that for as long as anybody could recall.
Astronomical/geological time doesn't seem likely to be invoked in the works of Lewis (who was writing before astronomers knew just how long stars lived), but the wider point occurred to me too - the ruins of Charn were in mighty good shape even if you allow for the complete extinction of all mold and bacteria. As if even wind and rain had lost their energy.
When reading the books in chronological order, almost the first thing we learn about Jadis is how she killed everyone in her world rather than let her sister win. Skip ahead to the end of The Last Battle and Aslan kills everyone in Narnia's world rather than let Tash win. And then he erases the sapience of every creature that doesn't love him in that moment. Whatever your thoughts on Lewis' idea of God, "Not a tame Lion" is kind of an understatement...
It's not a very close parallel. Jadis was willing to kill everything and sit in a Room Full of Crazy forever just to avoid losing. Aslan can't 'lose' to Tash (he's a Boring Invincible Hero after all), he just wants to preserve "the good bits" of the universe he built before shutting it down. I'm not a fan of Raptures or Omniscient Morality License in general, but I don't think those two situations are very similar.
The end of the first movie. It took the four children what, a minute to fall back from Narnia to England? And in that minute they regained a lifetime of memories, regressed back 15 years and got cut off from their home, friends and country. Seriously how could they cope with that? They're given no warning, no preparation, NOTHING. Imagine waking up everyday and realizing that hey, you're not in Cair Paravel anymore, and may never go back there. Or thinking 'oh I need to talk to Mr Tumnus/Mrs Beaver about...' and then remembering oh sorry they're gone. The weeks after coming back would have been utterly, utterly devastating. They'd been lost, confused and have no idea if they'd ever go back. To have to rebuild yourself after losing your entire life...its horrific.
Turned Up to Eleven in Prince Caspian. They go back to Narnia! Yay! But...everyone they know is dead. Imagine every single one of your friends and everything you built being destroyed. You never got to say goodbye or mourn them. That's it.
In the third movie, they've "defeated" the green mist thingy, and now you have at lease a dozen boatloads of people in the middle of the sea, stranded hundreds, if not thousands of miles from their homes. Just what happened to those people?
They have a somewhat crowded and uncomfortable ride to the island with all of the swords and sleeping lords to resupply followed by a longer journey home. Even if they have to tow all of those boats to move everyone at once they still have plenty of people so they can have rowers on the ship's oars constantly, reducing the amount of time it would take the Dawn Treader to return home. If taking everyone at once is not possible, then sending more ships after the Dawn Treader has returned home is also possible. They should be just fine, if somewhat uncomfortable, until they are safely back in Narnia or wherever else they came from.
The sleeping lords' island had plenty of trees on it, and the people on the boats were from seafaring cultures. Chances are, if the Dawn Treader left them some tools and sailcloth, they could build their own ships to sail home on after a few months' work.