So apparently, you can't actually make a canon from bamboo, and handmixed gunpowder made on the fly. (1) It is nearly impossible to get the gun powder mix right. (2) Even if you do the bamboo needs to be reinforced by metal to keep from blowing up in your face.
So here's what happens if you get "lucky" in getting the gunpowder together right. Good thing Buster was wearing a red shirt.
*Gasp* Science fiction is fiction?!
Trek Movie has a summary here.