Welcome to the site, Spieltrieb!
On the last two movies they've used fans as extras - more so with Colour of Magic. When they made Going Postal in Budapest, fans had to make their own way there and there were much less fans used.
I'm assuming they'll use Budapest again for this new one. Hopefully we'll have more details eventually.
“Men never commit evil so fully and joyfully as when they do it for religious convictions.” – Blaise Pascal