Flashback
interjected scene that takes a narrative back in time
A flashback is a technique used by writers which is often used in movies, television and literature. It involves a character remembering something that happened to him in the past. Scrubs is a television show that uses flashbacks often.
The term is also used colloquially, to describe lingering effects of a drug (such as LSD), or memories of a bad experience triggered by things in the present.