Canada might. They're pretty tight with the US, and fake US currency is still a diplomatic problem for them. Film in Iran, however, and they probably wouldn't care at all.
Yeah, agreed. Plenty of places will accept US currency at par with Canadian, and many cashiers have no idea how to check if the money is genuine, if they check at all.
A flood of fake US $20s in Vancouver could really screw people over.
A flood of fake US $20s in Vancouver could really screw people over.