[quote=jay420] how do you tell if your bud has mold in it before its too late, will you see it?
Yes, on the insides of the bud first. Looks like mold, or really wet brown plant material.

Do you actually have to open the bud to look inside?
Yes, if you want to catch it in it's first stages. Soon after though you may be able to see it on the outside as well.

Also how do you prevent mold in your bud if its planted outside somewhere, is there an easy remedy?
Nothing easy. When you plant outside you'll loose weed. That's the way it goes. You can't prevent it, but some things might help. Indica varieties tend to be more dense than sativas, therefore sativas may be better suited for rainy environments. Their fluffy light buds don't hold as much water. Some people spray with an antifungal, which adds moisture, so don't do it when it's wet. I sometimes plant under a tree and sacrifice yield in exchange for a little rot-free weed. Sometimes I'm forced to harvest early and get a different high than I was hoping for.