Board Thread:Support Requests - Community Management/@comment-37359701-20181210051421/@comment-5558012-20181210061943

I think a great minimum for references is requiring them for information that fans would likely challenge (such as a character's age) or for any type of statistic (such as number of episode viewings or film grossing).

Some wikis are much stricter with references, requiring specific reference details for almost every claim. Such a policy may not be necessary. I'd recommend reviewing how often claims are disputed or incorrect before going all out. Keep in mind too that a reference doesn't have to have a reference tag and can sometimes be included in the text itself.