When I Was a Partisan.

The film deals with the Lithuanian partisan resistance. An actor is playing the part of a partisan in a play called "Bunker". During the play he experiences a hallucination and starts believing he's a boy who lives in post-war Lithuania. In 1948 the boy made a mistake which cost the lives of him and the wife of a partisan. Back in 21st century, the actor has a chance to fix that mistake.