So is there any restriction in referring to various film titles in, say, a novel? And what about if a novel’s character passes judgement upon a certain film or any of its cast members?
Apologies in advance if this is a silly question.
You can reference anything you want. Just don’t include a pirated copy of the film with your book. 
IANAL, but… A work of fiction is no different than a film review. You can say what you want. What you cannot do is make your story look like it was written by the same people as the film (unless it’s obviously silly), use characters that are developed as part of the film James Bond or Spiderman are the property of those authors/owners. You can mention them in passing, but if they show up as part of the story, you are using characters that someone else owns. (Parody has a copyright exception, but tread carefully) Even internet, not for profit, won’t always get you off the hook. People own their characters and you cannot write them into a story because the character may be used by the owner in future stories, and if you write something (in depth) to impugn that character, you are damaging potential earnings. Disney, for example, gets very very upset when they find porn versions of their charcters.
You can’t be sued, for example, for saying “Gone with the WInd” is the stupidest movie ever made. You can’t be sued if one character remarks about a situation “this is just like what happened in Lord of the Rings”. However, standard libel and slander laws apply to the producer, actors, and any other real people.
If your story steals too many elements from a work of fiction or film, they may sue that you are stealing the idea… but that’s hard to prove. Battlestar Galactica (the original 80’s series) was sued by the Star Wars owners because it was all about guys in little ships buzzing around in dogfights with the evil ones who were trying to take over the galaxy - but that was a waste of time and the lawsuit failed. Many of the other elements weren’t there, and it has to be pretty close to win.
Just because one book or film is about boy wizards or vampires or a quest for a magic ***** does not mean that nobody else can write something similar - otherwise the only “ancient past” fantasy in the bookstores would be Lord of the Rings and the Myths and Legends of King Arthur.
I agree. You can reference any copyrighted work. You can even quote small snippets like a catchphrase (except for song lyrics). The former is not a copyright issue; the latter is fair use.
In addition, titles cannot be copyrighted, so there’s no issue.
What if, for example, the serial killer is a huge Star Trek fan, and the investigators have to watch specific episodes, with descriptions of what happens as it relates to the story? I’m thinking there’d be a polite letter to Paramont required there somewhere.
You can write descriptions of Star Trek all day long. Notice all those tv sites online where they recap every episode at astounding length? Doesn’t matter whether it’s fiction or nonfiction.
You can’t copy dialog. You can’t copy specific characters. You can’t even copy so many specific incidents that it becomes overwhelming. (See Universal City Studios Inc v. Film Ventures International Inc., wherein the producers of Great White lost to the producers of Jaws.) But you can describe and paraphrase and comment on and reference.
And you don’t need to put in trademark symbols, either. That’s the company’s job, not yours.
Here we delve into ‘folk law’, or ‘crap people think they know about law that is utter nonsense’. Another example of this is the idea, utterly unfounded, that saying “All properties are property of their owners” or similar does something beneficial for the author. It doesn’t. You don’t need to say that Star Trek is owned by Paramount; that is known, and you saying it won’t make anything that isn’t already legal for you to do legal for you to do.
IANAL, but it seems it would be much harder to claim that someone was trying to imply a connection between your work and their company if you explicitly say that you are not affiliated.
And if these disclaimers don’t matter, why do so many companies use them? These are companies that have a ton of lawyers. Take a look at just a basic Google search for the phrase. They sure seem to think it’s important.
IIRC, King used snippets of song lyrics in Christine.
Perhaps, but if you read the copyright notice in the front of the book, you’ll see that permission was granted by the copyright holder of the song. King is able to do this because his publisher has no problem paying the licensing fees – they are minor cost compared to what the book will bring in.
I also love it when people take the time to write out in large text “No copyright infringement is intended”. Pure lawesome.