User blog comment:TimeShade/The Crisis Has Arrived/@comment-1783334-20191207071212/@comment-28109177-20191207073529

Well if those show are involved they confirm they exist within the same shared multiverse so it's all canon. Smallville existing in the Arrowverse is still a lot of me to process hopefully the crossover will explain how these world coexist. The Admins are handling that situation with an easier approach.