I'm writing a story where the main character is going into different parallel universes.
Can you get in trouble for referencing a real person or thing if they’re in one of those different universes?
Writing Stack Exchange is a question and answer site for the craft of professional writing, including fiction, non-fiction, technical, scholarly, and commercial writing. It only takes a minute to sign up.Sign up to join this community
I'd say the golden rule is: If a person or thing is recognizable in your alternative universes, the fact that they exist in a universe other than our own makes no difference.
Meaning: If it would be okay to mention them in our universe then it would be perfectly fine to mention them in your parallel universe.
Hope this helps.
As I know, some video game companies had problems with celebrities because of characters who were similar to them. I think it does not depend on the universe (real or parallel) - it depends just on the fact that you use a public figure in your story. You have to be incredibly careful not to include undesirable information about this person. Also, if you write about someone who you know personally, you should ask their permission.
Unfortunately, I do not have appropriate links at the hand now, but you may look for good articles on this matter like Kathryn Goldman’s How to Use Celebrities and Other Real People in Your Story or Kathy Murphy’s Keeping It Real: A Rough Guide To Using Real People As Fictional Characters. These articles are not very fresh but still work.
Hope it helps!