Over 600 people registered for Culture Japan Night Jakarta Summer 2012 but about 100 of that could not make it due to the venue change. I was tipped off that I would be arrested (or fined or both!) if I held an event in public with 600 people without a permit.
It wasnt until only 2 hours before the event that we managed to secure a location - a ball room at the Borobudur hotel that I was staying at.