French movie I saw in the mid-70’s.  2 girls ingest a drug that takes them to a scene that keeps playing out over and over again every time they go on a “trip”.  Very similar to Celine and Julie Goes Boating.  The two girls eventually realize that a murder in the future is going to take place and they take another drug-induced trip to the scene and try to prevent it.  I seem to recall that the one girl realizes that it is a real scene from the future because she notices a newspaper with a future date on it in “the scene”.