Using this exploit you can have 2 shots in one (ometimes 3 or 4 if you have a bad lag spike).
When you are in Uldum doing the fire from the sky quest, you will be put in a catupult to rain fire down on some dastardly soldiers. Your skill bar will alter and you will have 1 skill.... to fire a flaming ball of death.
I'm basing my exploit on a faily standard latency of 50-100ms though it should be possible with better pings.
Please note, this will only effectively work for people who use keybinds. If you are a clicker you will not be able to do this.
Basically, hit "1" or whatever is your bind and when your cursor becomes a target get ready. When you click "fire" (your left mouse button) hit the "1" key again immediately. you can now fire again.
I have tested and if you spam 1/click/1/click you can place 2-5 targets in close proximity OR just click it once and have yourself 2 shots wherever you like.
Basically you can halve the CD on the missiles.
This may be a minor exploit, but 1/2 the CD means 1/2 the time it takes. It also makes it easier to hit a group by placing several in a line.