This is just my thought on this but I would guess there is an air cannon, fog machine, and a light involved. The fog is at the base of the cannon and the air cannon pushed the burst of fog out simulation gunpowder smoke. (personally I would insert a cross cut fabric piece about half way up the barrell to serve as a fog reservoir so you don't have fog constantly rolling out of the barrell)
I suspect the solenoid for the air cannon is electric and the light is probably wired in the air cannon's circuit so when the air cannon goes off so does the light. Now with that said you are probably dealing with a system that is wired for 120VAC and could use either a 120VAC or possibly stepped down for a solenoid that might be 24VDC or something to that effect. If it's lower than a 120VAC that get's into a few complications that have to be worked out but it can be done with a bit of work.
Check out the below sites too:
http://www.effectspecialist.com/custom.htm (This is just a cool site but shows a mortar cannon about half way down the page)
Hope this helps some...