Are there any legal cases regarding trademark infringement when a name is used inside a work? E.g a video game containing a location named using a trademarked name.
You cannot copyright or trademark a name. Trademarks typically are more than just a name, but include stylizations including font, coloring, logos, or other icons and symbols. For example, The Golden Arches of McDonalds or the Nike Swish logo. In writing, these two symbols are difficult to reproduce so saying "He laced up his Nikes and went to grab a burger from McDonald's" is not a copyright or trademark violation. Hell, naming a character Clark Kent is not a violation of Copyright, so long as it's clear that he is not the more famous Clark Kent in even the slightest way.