That's won't explode by itself. Something would have to super heat (i.e. another fire) the canister and make it rupture which could result in a big flash fireball from the extra oxygen present in the nitrous. (that's what makes it work in jets and cars you know, extra oxygen, not the fact it's a super fuel like gasoline)
We use nitrous oxide all the time at work and we also use it to scare the newbies; someone opens a valve and sticks fire in front of it just to watch the newbie run away screaming. It's great fun.