I was thinking about the different types of humor and the ways they are expressed in movies and books and tv shows.
The most common way is the clueless person who is expected to be smart. For example, a person in a position of authority who is actually a doofus, but must be taken seriously by everyone. Kind of like Michael Scott.
Another is when two people are talking about different things, but are assuming they are both talking about the same thing. I remember watching The Ladies Man and a Catholic Nun was talking about the Yalu River in China and he was talking about the Yellow River.
People taking trivial things seriously. This happens a lot, basically actors being too serious for a given situation.
Often times it is a merging of the person watching the joke and his/her expectations with the expectations of the actors or characters in the show. That mismatch can create humor.
Also, in LOTR a big theme is people making a decision about an issue or idea, and trying to act on it, only to find it is a moot point. There are many examples of this. Gandalf dies fighting the balrog, giving up his life to protect it, only to be granted another life by the Gods. Aragorn, after taking Gondor, takes his army on a suicide mission to attack Mordor and draw out their forces, only to have Frodo destroy the ring at the last possible second, saving his life. In Tolkien's book, it is often more important what people decided to do rather than what was actually done, as external forces conspire to change the reality of the situation after characters decide to act, but before they can actually do so.