If you load an autosave, you'll notice the following things do not happen.

Any unit that is about to be completed is deleted instead. The production will clear out, but the unit never appears.

If you hit enough fame to recruit a new champion, you lose the opportunity to get that champion.

If you were under attack by creeps, they no longer attack you.

If you were under attack by computers, they no longer attack you.

This effects the computer players as well. You can effectively halt the computer's expansion, even at the highest difficulty, just by setting autosave to every turn, and loading the game every turn. This bug is very easy to test for and repeat.  Probably the best fix is for autosave to save at the end of your turn, but before it processes anything past that.  Also, at the same time, they should really allow you to up the number of autosaves from 2 to 5 or 10.