Script Supervision and Continuity

The Script Supervisor or Continuity Supervisor is responsible for maintaining a film's continuity. Since scenes are shot out of order and multiple angles are shot to cover a scene, the Script Supervisor makes sure everything remains the same. A continuity error can ruin the illusion of realism and affect suspension of disbelief, so it is the Script Supervisors responsibility that everything can be edited seamlessly together. 


More information:
http://scriptsupervisors.co.uk/

Skillset page about Script Supervisors


Books:
The Continuity Supervisor by Avril Rowlands
Script Supervising and Film Continuity by Pat Miller