When David is blindfolded in the car after being kidnapped, it is tied differently from when he is put in the room blindfolded.
When David is first put in the room, and he still has the blindfold on, he feels his way along the wall and his finger tips are seen rubbing on a picture frame. The camera angle changes and the backs of his fingers are seen running the frame.
After chasing off the wolf by firing his gun, Vince (Joel Edgerton) says, "God bless the fifth amendment." The United States Constitution's fifth amendment protects against self-incrimination and requires due process be afforded. He probably meant the second amendment, which protects the right of the people to keep and bear arms.