In the flashback scene at the beginning, Franklin cuts down the swing. As he's carrying it away, he turns to go back to the tree to cut it down. You can see the swing hanging from the tree again as he approaches.
When Franklin is sweeping up glass on the floor the glass doesn't move as the broom sweeps over it, so presumably it is CGI or added in post production.
There's no good explanation as to why Denise didn't call the police on her way back to her grandparents' house.