See here for trivia tropes related to the Peter Jackson films.
- Ashcan Copy: The 1966 short film directed by Gene Deitch, was made for this purpose (more info here). According to Deitch it was screened only once in June 1966 to an audience of about six people to fulfill the part of the contract saying the film had to be shown in public. Despite being the only screen adaptation of Tolkien's work produced when he was still alive, he never saw it (leading Deitch to say "Thank God!"). The story included a Princess for Bilbo to romance, and discarded many basic elements of the story, such as the dwarves. Gandalf ceased to play a part after they depart for the Lonely Mountain. Characters were renamed (Trolls became Groans, Goblins = Grablins, Gollum = Guloom) and the dragon Slag (not Smaug) is dispatched by Bilbo, the Princess and her retainers.
- Breakthrough Hit: The success of The Hobbit encouraged J. R. R. Tolkien to write a much larger novel about Middle-Earth, which turned out to be The Lord of the Rings.
- Recycled Script: In The History of the Hobbit it's pointed out that Thranduil the Elvenking and his hold in Mirkwood is closely derived from the original conception of Thingol of Doriath (Tinwelint of Aranor) — which also explains his distrust of dwarves. This isn't obvious to people who are only familiar with the published Silmarillion, because the final version made Thingol and Doriath much richer and less earthy and sylvan. However, Tolkien added a Discontinuity Nod to this when The Silmarillion does mention that Thranduil lived in Doriath in his youth and modelled his own kingdom in Mirkwood on it.
- Referenced by...: The source code for Perl 5, which does quote The Lord of the Rings many times, also quotes The Hobbit once, at the top of numeric.c.
- What Could Have Been: See subpage.
- Cut Song: Old Fat Spider, which in the book was sung by Bilbo to taunt the Mirkwood spiders, is on the soundtrack but not in the movie. There are also full versions of the second Misty Mountains Song and second In the Valley Ha Ha which only get one verse in the movie.
- Orphaned Reference: The first encounter with the Wood Elves is cut, which means the first actual reference to them is saying they had returned.