I missed to pick up all the snake scales and beeing already on day 5 I can't get the scales from Jackson Square fortune teller or Mdm Moonbeam. This isn't listed as an unwinnable situation but Mosley doesn't react to my 2 scales. Can I advance from this point on or is it all the way back to day 3?

The main snake scale you need is at Lake Ponchartrain, which you can still pick up on day 5. The scales from Moonbeam and the Jackson Square Fortune Teller are not available on day 5, but are not truly mandatory to complete the game. They are simply worth extra points. You should be able to complete the game from your position on day 5. Now, if you want all the points, you'll have to back up to day 3.

Thanks, I tried again and now it works. I don't know what I made wrong before, but I guess I confused myself with too many loading while testing different things.