I am improving the save feature, but I believe these errors are from one of three causes:
1. Mouse moves over an item while it is loading. I will fix this, but in the meantime keep your mouse outside the frame until the game is fully loaded.
2. Save your game with your inventory displayed. Don't save when pressing buttons, moving things, or viewing the map.
3. WebGL gives us a lot of heartache when saving and loading. We will be switching to local builds around the time the KickStarter comes out. Hope we'll have your support! Should be in the next week or so