Are you allowed to write about your characters going to Disneyland? Or is there some kind of copyright law?
im pretty sure your allowed. i read product placement all the time. its usually someone drinking a pepsi or blowing thier nose with a klenex but its there. i know there is such a thing about parody protection. that is how people like south park and SNL can make fun of anyone they want and no one can do anything about it. i would make sure. and i dont think it would hurt sending an email to the disney company and ask permission to write about them in your book. dont take my word for it because i do not know for sure.
Copyright isn't an issue. Trademark could be, if you write them going to a ficttional place whose name has been trademarked. Libel could be a factor if you take them to Disneyland and the rides are lethal or the costumed Mickey Mouse is abducting and raping children who stray from their parents. The names of real places aren't protected as intellectual property, unless you try to open your own competing place with the same or too similar a name. That's why a fictional place in fiction can be a trademark violation - you are infringing on intellectula property in a directly competitive context. Defamation (libel in writing, slander in speech) can be a factor if what you write or speak about damages the reputation of a real entity. Whether damage has taken place is largely decided by the plaintiff, but verified or denied by a judge or jury if it comes to trial.
There will be no libel, just a simple trip to Disneyland, where some of the story unfolds. Disneyland is just the setting.
