“World on a Wire” (or “Welt am Draht”. 1973) is a television film (two parts, over 3 hours total) by Rainer Werner Fassbinder, based on a “double worlds” transition that foreshadows ideas is Christopher Nolan’s “Inception”.
In his 2011 book "The Hidden Reality", Brian Greene discusses simulated alternative universes in a chapter toward the end. This will be covered on my Book Reviews blog soon.
For a distantly related short film. try "The Afterlife Dysfunction" (9 min) about consciousness and quantum theory here.