Writing a commercial movie that's a massive multiplayer franchise crossover is such a highwire act cus you need to give off the impression that the characters could go anywhere or meet any fictional characters, but behind the scenes everything needs to be either licensed or public domain and it can be really hard to avoid making it obvious which licenses the studioowns, what the terms of the product placement deals where and where they are padding it out with public domain references.

There's a very funny example of this in the end credits of Wreck it Ralph 2 where the end credits are studded with icons that represent sites and things you may encounter online.

One of them is "Sherlock fanfic", another is "Jane Austen roleplaying", then there's an off-brand mention of a certain wizarding franchise and it's VERY obvious which one of these three isn't in the public domain.

"Sherlock fanfiction" I thought was especially clever, cus I can tell they are referencing the BBC Sherlock, which would make it a reasonably topical internet fandom culture reference for the time (maybe like five years past its prime when the movie was releasee, but still), but it's pretty clear they can do this because Sherock Holmes is in the public domain.