If you haven't noticed, I liked The Last Jedi quite a lot -- so I was quick to ask for the tie-in Visual Dictionary for Christmas this year. Beyond just being another way of making money off the Star Wars name (though it's definitely that as well) the dictionary has the answers to a lot of the questions I had after watching The Last Jedi.
How did they drop bombs in microgravity?
The Visual Dictionary clarifies one big question people were asking regarding the bombing run at the start of the film -- no, the bombs don't actually require gravity to drop, it's a tricky mechanism involving electromagnets. Here's what the book says:
"Bombs don't technically "drop" in microgravity, but are impelled from their racks by sequenced electromagnetic plates in the clip. The bombs are then drawn magnetically to their unfortunate targets."
As a neat little detail, some of the bombs also have little messages written on them from the bombing crew. One says "Hi Snoke" in Aurebesh text while another bears the message "Han says hi".
Does Admiral Holdo dye her hair?
Is Holdo's hair naturally pink through some kind of space magic, or is it the Star Wars equivalent of a blue rinse? Turns out it's the latter -- the book says her hair is "frequently dyed ... with chromomites".
The rest of her look also has symbolic significance not mentioned in the movie, harking back to her homeworld of Gatalenta. Her halo-like tiara represents the system's multiple suns, for example, while her silver bracelets depict local constellations. Even her blaster is one that's distinctive to Gatalentan nobility.
What's with Snoke?
The movie didn't really offer much new information on Snoke, but it did show him in all his flashy-robed glory.
The dictionary gives a little extra details, like pointing out that he is "powerful in the dark side of the Force, but he is no Sith." It's also vague on his physical deformities, mentioning "whatever frailties have broken his body" but not going into detail on what that might have been.
It also turns out that under his OTT gold robes are... similarly OTT gold slippers. "Snoke's painful stance has caused him to prioritise comfort," says the caption on this picture of his intricate padded gold slippers. Well, at least he knows his style.
What are those weird sea cows?
Turns out they have a name beyond being 'those weird sea cow things Luke gratuitously milks'. They're called Thala-sirens, and apparently the reason they're so chill with Luke just walking right up and milking them is because they have no predators on the island, so they're happy to hang around for a bit of sunbathing.
Who are the fish nuns?
The fishy-looking nuns on the island are called the Caretakers, but beyond that they're a species known as the Lanais. The ones who live on the island are all female, while the males are known as Visitors and spend most of their lives out on the oceans fishing.
The Lanais care for the Jedi structures left behind on Ahch-To but otherwise don't see to care much about the Jedi. They follow their own religious system, and aren't particularly attuned to the Force. They just like cleaning, I guess?
Did Luke keep Darth Vader's lightsaber?
Another thing on Ahch-To that was only briefly shown but clearly had a whole lot of backstory to it was Luke's collection of objects in his hut on Ahch-To.
There was the compass, an old Jedi relic apparently recovered from one of the Emperor's hoards of old artefacts. The compass is attuned to 'hyperspace vectors' rather than the magnetic fields of a terrestrial planet.
You may have also noticed the necklace made from the remains of a lightsaber with a red crystal inside. While many have speculated it was made from the remains of Vader's lightsaber, the book instead calls it a "Jedi crusader pendant" from before Luke's time, made from a "fragmented lightsaber crystal".
I could go on forever with the little snippets of canon information in this book, but here are just a few I found interesting. If you've seen any curious background trivia for The Last Jedi, chuck it in the comments!