Mine crashed, lost none of my found items, but lost all the efficiency, tank size, and thrust improvements. To make it worse they were still missing from the world so I couldn't find them again.
Ick. I think the save game functionality is a bit buggy. I wish they'd just have an option to base64 the whole state (findings, upgrades, location, facing, and velocity) into a URL parameter so you could just save the game as a shareable URL.