There could be the following reasons why you may have these issues:

1.You’ve got a lack of memory on your device 
2.You’ve got an outdated version of Rovercraft 

Please contact us via our in-game Online Support Service if you have a different issue. Describe the issue in detail:

1.What exactly is wrong 
2.What you’re doing that leads to the problem 
3.When the problem occurred for the first time