Right before the game auto saves if you're in the middle of doing and action Such as DIG or Build Tile or ladders or pipes etc. OR even cancel or deconstruct, the action could create very unintended behaviors specifically applied to something way off screen. No where near your current view sceeen.
Example: I click on a dig tool. Not even clicking on anything, as the game saves, the game might randomly place your digs somewhere off screen. It may even drag it entirely across the screen off screen if you're in the middle of a drag.
Often times, when I explore the map I'll end up finding random build/digs in an unknown area that gets uncovered to reveal these random actions made a couple of cycles ago.
Perform some action while auto-saving.