Continuity

The definition of continuity is:
 con·ti·nu·i·ty  

/ˌkäntnˈ(y)o͞oəitē/

Noun The unbroken and consistent existence or operation of something over a period of time. A state of stability and the absence of disruption.

In media this would mean there is a mistake in the film in which something is not consistent, e.g an object appearing or disappearing in the scene. Here is a short video explaining continuity and examples of this problem: