Dream sequence

A dream sequence is "a technique used in storytelling, particularly in television and film, to set apart a brief interlude from the main story." Its two jobs: sequences "shed light on the psychical process of the dreaming character or give the audience a look into the character's past." Cinema used it early, from Sherlock Jr. (1924) to the Dali-designed dream of Spellbound, The Wizard of Oz builds a whole frame on it, and Dallas famously absorbed a season into one, since a writer can "retroactively explain past plot elements as a dream sequence in order to maintain a plausible continuity."

That absorbency is the danger: a dream can erase anything, and "it was all a dream" reads as a cheat when it cancels stakes the reader paid for. Used openly, the sequence works as a licensed flashback or flashforward, a step into nonlinear narrative whose logic may bend where waking scenes cannot.