In one of the opening scenes, when Kelly drives away from her apartment she is wearing large, golden hoop earrings. When she's shown in the car she's wearing multi-colored teardrop earrings, and when she arrives at the family cabin and disembarks from the car the golden hoops are back.
After the twins' car crash, one of them has a wound on her thigh that's bleeding profusely like a running faucet to the rhythm of her heartbeat--a telltale sign of a ruptured femoral artery, and at that rate of blood loss she'd be dead within 2-7 minutes, especially since her twin removed the strap she had tied around her leg to stave off bleeding.
When Janna and Fiona run out of the cabin, Callie grabs a shotgun and takes off after them; as she chases them the cameraman's shadow is visible, running alongside of her as she runs down the trail.