TestFlight any App security issues?

So I have started beta testing my game using TestFlight with some friends I know. Everything is working fine.

Now I wish to expand my testing by including many more beta testers who of course I would not know. I would just invite them to test the game for me.

Are there any security risks with doing this? ie. Could they grab the app and then distribute it on jail broken phones? Or somehow get access to my source code since the app is running on TestFlight?

Thanks for anyone that can answer my concerns....