You guys should watch this movie with Tim Robins called "Jacob's Ladder". Similar idea to the multiverse theory. A vietnam vet gets shotup badly and is taken to the hospital. He then wakes up and realizes it was only a flashback nightmare. He continues to live his life years later but strange events keeps on occuring which eventually led up to him finding out he was infected by a chemical agent in vietnam. The film ends with us finding out that he never actually made it ouf of vietnam, and that his whole life experience was just a "dying hallucination". Frickin trippy...

Another interesting "multiverse" a short story is An Occurrence at Owl Creek Bridge.