Thanks for trying out and helping us test the Overwatch World Cup Viewer today.
We have just patched this client to address the “reversed teams/sides” bug (and a couple other minor bugs). If you are running this client and would like this update, please exit to the Battle.net App and wait for the patch (or you can select Overwatch, Overwatch World Cup Viewer, Options, Check for Updates).
After patching, the Battle.net App should show Version: 18.104.22.168.52647 at the bottom. Let us know if you encounter further issues and enjoy the rest of the 2018 Overwatch World Cup!