I've had quite a few, some similar to the above:

Broken zippers (clothing, tent screen door)--same fix as Kent.

Stitching started to unravel where top of new pack sewn to extension collar--survived the trip and Ron Moak of Six Moon Designs fixed at no charge. He didn't just resew where the stitching was loose but sewed twice all the way around the pack to reinforce it!

I shortened the excess hip belt straps on said pack to save weight, but like an idiot didn't fold over and hem the ends of the straps. At the trailhead for a trip last summer, I found that half of the belt buckle had fallen off. Temporary remedy: Removed the other half of the belt buckle and tied belt ends in a square knot. It worked for the trip. Permanent remedy: bought a new buckle and hemmed the strap ends!

Netting of tent door tore loose from zipper; easily sewed back on. I discovered that a small pebble can be used as a thimble substitute, as it was hard to get the needle through the zipper tape.

Another one from last summer: the seat of my pants completely disintegrated (pants were 10 years old, so not surprising). It wasn't a case of a hole to patch but of the whole seat in shreds! Remedy--tied my wind shirt around my waist and let the tail hang down to hide most of the rather large gap. All the people we met on the way out politely did not mention my ragged state. Fortunately I had jeans in the car to wear on the drive home! (My grandson, who was with me, would never have let me drive back without stopping at the first pizza place we encountered!)

Tent leak, like W_D's, due to gap in seam sealing of new tent. Had tiny tube of sealer with me. Prevention: after seam sealing, test tent with garden hose! Do this at the beginning of each season, or at the end when you are cleaning tent for winter storage anyway.

Now the biggest repair I ever experienced, although my father did most of it (I was 12 at the time): It was the 4th day of a 6-week horsepacking trip. We were in northern Colorado, on what the map showed was a trail but obviously had not been cleared for at least 10 years. We came to a log across the trail, which was low enough for the horses to walk over. However, the lead pack horse decided to jump. The second pack horse decided no way and pulled back. The lead rope connecting the two horses broke, and second pack horse took off down the trail at a dead run, bucking and smashing his pack into trees as he went. Pieces of the pack were strewn along the back trail for several miles. The wooden panels of the antique cowhide panniers broke in several places and so did the wooden pack saddle. Fortunately, there was a nearby abandoned homestead, with quantities of the standard Western repair material, baling wire (this was in pre duct tape days). My dad drilled holes (with the leather punch on his pocket knife and a hot wire) and ran baling wire through them to hold together the wooden panels of the panniers, the pack saddle tree and the broken leather straps (except where the strap would rub against the horse, where he used leather lacing). He heated the baling wire slightly so it would shrink tighter when it cooled. The repairs held up for several years! In the meantime, my mother and I hiked the several miles of trail picking up the pack contents (mostly food and cooking gear). There was a lot of it! The very last thing we found, in dense foliage behind a tree, was my father's checkbook! (This was long before the days of debit/credit cards, so the checkbook was our only source of extra cash.) We of course had to lay over a day to accomplish these repairs. Interestingly, the horse was evidently scared into behaving himself ever after--we never had any more problems with him! When we left, we abandoned the trail and followed the road! I'm not too sure how this would work today, given the rarity of baling wire and that duct tape, its modern equivalent, wouldn't have done the job.