So you're out for a ride, and things are going great then suddenly life throws you a curve ball... Your bike breaks. Maybe it's just a flat, maybe you snapped a chain, maybe it's extreme enough to break your frame. The point is you need to be able to fix things enough to limp back home or if you're lucky finish the ride without further issues.
Now in most cases if you break a frame on a ride, you're walking home. However depending on the location of the break and the materials available, you might be able to patch it together well enough to limp back home.
In this case, the frame broke at the top of the seat tube. The seat post still had a few inches into the rest of the frame but every bump resulted in the seat post popping off the bike. The solution wasn't elegant, the draw string from a pair of shorts was used to tie the seat down to the frame. It still pivoted at the break but was secured in a way that it couldn't fall off.
If you bike, you've probably found yourself fixing a flat. A simple patch kit or spare tube should be considered essential tools for all cyclists. But what if it goes beyond a basic puncture... what happens if the tire itself failed and you have a hole in the tire itself? Obviously the tube will bulge out and puncture very quickly. However is you happen to have a piece of sturdy plastic, or duct-tape, or even some paper money (US money works better than Canadian and comes in smaller bills), you can apply any of these to the inside of the tire to prevent the tube from bulging out. The reason money works so well is that it's not actually paper, it's a combination of many things and is closer to fabric than paper, but it stays strong when wet.\
Another essential tool is a chain tool... it does not have to be huge, my small multi tool has one. But if you ever need it on a ride you will never ride without one again.
A broken chain is actually quite easy to repair and be on your way. Simply use your chain tool to take out the broken link and re-attach the now shorter chain. You will have to be careful not to shift into gears that require longer chains such as the larger chain ring to larger cassette gears, but that's a small price to pay for finishing your ride.