In the barn, as Sam looks for the keys to the cuffs in his jacket, you can hear the cuff come undone, and see it fall away from her hand. As he pulls her to the ladder, she grabs onto the cuff so it's not completely free. Then they wrangle the cuffs back onto her as it's just part of the scene.
Although this episode takes place in June 1976, Diane watches The Bionic Woman (1976) episode Out of Body (1978), which was originally broadcast on March 4, 1978.
When the sheriff comes to Arkansas and picks up Diane at the motel, the lightbar on the police car is a type not manufactured until the late 80's or early 90's.