Do The Good Place creators need authorizations for the name dropping?

The show is clearly meant to be comedic both in general, and with regards to the references in particular. Furthermore, the show is clearly fictional, and Tahani is presented as such an unreliable narrator that it isn't clear whether her claims are true even within the show (although some of her claims have been shown to be true within the show's universe). Given these facts, it would be extremely difficult to make a defamation case; defamation requires that the claim be presented in a manner that a reasonable person would take as a claim of fact. See

There wouldn't be much of an intellectual property case to be made, either. They aren't showing actual clips of the shows, so no copyright issues. It would be difficult to interpret the mentions as being endorsement of The Good Place, so no trademark infringement.

No. A. Not under Intellectual Property 1. Trademark doesn't apply since they're not selling a product under the name in a show. So, you violate a trademark when you sell a product they also sell using a confusingly similar mark. While it is possible a celebrity would trademark their name (Gwenyth Paltrow brand chakra stickers, for example) simply saying her name wouldn't violate that trademark. But selling "Gwynnyth Paltro" brand chakra stickers would. 2. Copyright doesn't apply since it's not expressive content.

B. Not under defamation. In order for defamation to apply, a reasonable person must believe the thing being said about them. This is a fictional show, and I don't believe that it would be found to be reasonable should someone think Tahani's celebrity stories are real. Many might also qualify as parody, which is protected.