Will you choose the very classic rice exit? It looks super old fashioned and cool! The rice won't hurt anyone, but it can and will get stuck in your up-do! I say sacrifice the 'do for the very cool experience! P.S. It's just a myth that birds who eat rice will explode!
How about the ever-festive sparklers? These are great around the 4th of July, of course, but can really be used any time. Timing is key to the success of the sparklers! As beautiful as this can be, be aware that these are live flames and the sparks are hot!
Perhaps some non-threatening petals? How could you go wrong with beautiful rose petals that are light as air and wouldn't hurt a soul? This is a wise and injury free exit!