From what I glean, live ammo is forbidden. Various blanks are easily recognized by the crimp ( but no mention of any markings on the head), realistic looking dummies have a bb in place of the powder so you can hear the rattle.
As for cannons, in Canada probably the military is the only allowed. In the US you can have one that will shoot solid projectiles, but not explosive shells.
Maybe the correct assessment is an amusement park. We trust that the rides are inspected instead of looking ourselves