It's my cakeday, but I don't have a cat.

Aragorn was part elvish, through his far off ancestor Elros, Elrond’s brother. This lineage lengthened his lifespan. Aragorn lived to be over 200 years old, and was a child living in Rivendell when Bilbo passed through during The Hobbit. He was only a year younger than Denethor, who had a onesided rivalry with Thorongil, Aragorn’s alias as a captain of Gondor, for the attention and favor of Denethor’s father Ecthelion.

The Hobbit was originally not set in Middle-Earth, and contained references to things like policemen in the Shire. In this version of the story, Gollum freely hands over the Ring to Bilbo as a reward for winning the riddle game. When Tolkein integrated the story into his legendarium, he made sure to correct those sorts of inconstancies.

The original dragons were wingless and as such had unarmored bellies, for enemies couldn’t attack them from below. This is why Smaug slept on the gold and jewels of Erebor, to create a scale-like coating of hard metals pressed into his underbelly, and was killed by Bard shooting him in a spot he missed.

(This one is for only movie watchers) The books following Fellowship were divided in half along their plotlines, one ‘book’ for the War of the Ring following Aragorn, Gandalf, and Merry and Pippin, the other following Frodo and Sam’s journey. In the Two Towers, Book 4 ends with Frodo being taken to Cirith Ungol. Thus, in Book 5 in Return of the King, when the Mouth of Sauron shows Aragorn and co. Frodo’s mithril shirt, the reader had no way of knowing if Frodo was in Sauron’s hands or not.

Faramir had the same prophetic dream about the return of Isildur’s Bane as Boromir did, but whereas Boromir had the dream once, Faramir had it three times. Denethor sent Boromir anyway, as he trusted his more martial son for such an important task. This is particularly important in the books where Faramir is completely untempted by the Ring, saying he would not take it even if he found it by the side of the road.

The ents were created due to Tolkein being disappointed in Shakespeare. As a boy, he went to see a performance of Macbeth and was extremely let down when the prophecy that Macbeth would only fall when “Birnam Wood marches” turned out to be an attacking army using branches from the wood to mask their approach. In response, Tolkien created an army of living trees and had them lay siege to Isengard.

Gandalf was in possession of one of the Elven Rings of Power. He was given Narya, the Ring of Fire, by the shipwright Cirdan when Gandalf entered Middle-Earth via the Grey Havens. The primary power of Narya was to inspire and encourage those around the wearer, which is why the Fellowship fell into despair when Gandalf, and the ring, were lost in Moria.

According to Tolkien’s notes, no one possessed the strength of will to intentionally harm the Ring in Mount Doom, where its power was at its strongest. Thus, it would only ever be destroyed by ‘accident’ implied to be subtle divine intervention.

The retaking of the Shire from Saruman’s goons was officially led by Pippin. He had been knighted by Aragorn prior to departing Gondor and was merely given indefinite leave to return home, not being dismissed from service. Since the Shire was technically part of the kingdom of Arnor, Pippin was acting in an official capacity as a lawman putting down a group of rebels.

Samwise, as he neared the end of his life, traveled across the sea to the Undying Lands, joining Frodo there. They, and Bilbo, were permitted to do so as a compensation for their trials in being ringbearers, although they were not permitted into Valinor proper.

Bill the Pony, set loose by the Fellowship outside Moria, was actually able to return to his previous home in Bree alone. When the hobbits passed back through Bree on their way to the Shire, they found him there and gladly took him with them home.