So many things...
After all these years I didn't know about "the fingers of blood"
This referred to the way that certain blood spatters point in the direction of travel.
And according to the tracker, her dog has revealed to her that most deer are trailed way too early by bowhunters and that they go down way closer to the hit location than we realize, but are often pushed out by tracking too early.
And she also said that older bucks have escape patterns that are way different than younger bucks. Not exactly a revelation but the way the dog reveals it to her was interesting. Many younger bucks mortally hit, stop close to where they were hit to try and figure out what has happened to them and as a result of that they often see the hunter moving around in the stand. Just lots of cool stuff like that.