Major problem with Sara

At the beginning of the movie, Sara dislocates her right shoulder. The Sheriff pops it back into place. When she first wakes up in the hospital, she reaches for the nurses call button, and she makes a small sound of pain. For the rest of the movie she is shown using her right arm with no apparent pain.

When people dislocate their shoulders, it is popped back in to the socket. They then put the affected arm into a restrictive sling. This is to keep them from reinjuring the shoulder and help reduce the amount of pain from moving the arm. The arm is kept in the sling until the shoulder has healed enough to begin rehab on it.