If someone wrote a book or something that used names copyrighted or trademarked by someone else, could they get out of trouble by saying 'insertnameshere are registered trademarks of insertownerhere'?

Names and titles are not copyrightable.

Names can be trademarked.

You can use (through fair use) ‘insertnameshere are registered trademarks of insertownerhere’. For example if you were doing softare documentation and you had to use the name of an operating system.

But you could probably not use a trademark in the title of a novel without permission.

…

Do you mean writing a novel in which you referred to someone else’s work? Like this, for a made-up example?

Tom crouched low and pulled his jacket up over his head, wishing he had Harry Potter’s cloak of invisibility.

Or this?

Lisa set aside the novel she had been reading. Betty glanced at the cover: it was Gone with the Wind.

I’m not a legal professional, but I’d feel sure there is nothing wrong with that and you won’t get into any legal trouble. If your work got published by a traditional publisher, you’d have the benefit of their legal department’s advice.

You can always look in the front of any book that does name names in this way and see what sort of disclaimer they use, if any. Some authors routinely allude to trademarked brand names as a way of including concrete detail; Stephen King is one who does this, and his books include a disclaimer about the fictitious use of real names.

If you’re writing a nonfiction book in which you discuss and analyze other people’s work or real products and services, it’s unavoidable. Consult similar books and look at their disclaimers on the copyright page.

I’m also not an attorney, but I don’t think that the use of “names”, even trademark names or names of characters from copyrighted works by others, are off limits – as long as there is no attempt to defraud the reader or consumer that you are the trademark or copyright owner.

For example, The Coca Cola Kid is an example of a literary (and movie) title that does not depend on Coca Cola’s permission to use the name. Likewise (though I hate to admit that I read it) American Psycho uses trademark and brand names extensively in the text, because part of the main character’s deviance is his apparent belief that his use of “better” brands somehow makes him an exceptional person. In that case, the use of the brand and trademark names in this way is a deliberate plot element.