Strange facts you learn by riding your bike a lot: a flattened cat can last for more than six months on the side of the road. Maybe that’s why tennis racquet strings used to be made with cat gut. Fresh banana peels are just as slippery as they are on the Bugs Bunny cartoons.
The only glass that gives you a flat are the shards you don’t see, I’ve never gotten a flat from riding over broken glass that I saw.
You can almost tell the season by the stain on the road from roadkill, in the spring there is not much of a mark left, but as the summer passes into the fall, the animals are fatter and leave a greasy stain that lasts for much longer.
Avoid the trail of liquid from garbage trucks, not only will your bike and gear stink if you ride through it but it can be as slick as ice.