Daniel, thanks for clarifying the flag. It was difficult to verify without seeing the image on it. When I searched for Nazi flag none of them looked anything like that. As for protestor vs. protester, here's what it says in an article by The Atlantic:

BUSINESS

Once and for All, It's Spelled 'Protester' Not 'Protestor'

That's with an -er, not an -or; go tell your copy editors.