No feature to save game
Quite simple ... why is there no feature to save the game when you exit.
Because it automatically saves when you exit.
This is an online game, all the data and settings are saved on TL's servers where ever they are.
other than the bugs listed, you dont have to worry about the state of your game.
force close errors on android do tend to have an adverse effect on the game state, but its quite stable.
you dont need to worry, your game and animals will be there when you start the game again.
hope this helps