Real Dictionary

flashback
countable noun: In a film, novel, or play, a flashback is a scene that returns to events in the past.

flashback in American English
an interruption in the continuity of a story, play, film, etc. by the narration or portrayal of some earlier episode
noun: a device in the narrative of a motion picture, novel, etc., by which an event or scene taking place before the present time in the narrative is inserted into the chronological structure of the work

flashback in British English
noun: a transition in a novel, film, etc, to an earlier scene or event
verb: to return in a novel, film, etc, to a past event