Especially on summer rides, I browse google maps for country gas stations or stores, and call them to make sure they are open. Two or three water bottles isn't enough, I need refills. Some churches have outdoor water taps, but it's getting kind of rare. If I ride past a church, I'll check it out for future rides.
A front and rear blinky is much safer. Even in bright noon sunlight, my Hotshot 150 flash is visible.
It's quite common to intermittently have no cell service on our country rides. Valleys that are just 30 miles from Cincinnati can have no service.
On the few occasions where someone in our small group has a flat, it's quite likely that a driver will stop to see if we are okay.
Punctures or broken shift cables are by far the most common mechanical failures.