When Brianna is locked in the electrical tunnel, she turns on the lights. In the book, there are no lights and Brianna must pass through by feel and intuition.
Brianna is driven to the damn in an old Land Rover.
The same style Land Rover used in the classic Land Rover advertisement driving up a damn.
The Damn used was the same damn used in Top Gear episode 4 of Series 22 that Richard Hammond recreates the Commerical in a Land Rover Discovery.
In interviews Charles Vandervaart who plays William, Joey Phillips who plays Denzel Hunter and Izzy Meikle-Smalls who plays Rachel all talk.about the fight that their characters had. They found it funny that the man who plays the husband who attacks them is in real life a Buddhist Pacifist and the woman who plays his wife who attacks Denny and Rachel was an ex MMA fighter.