Money can be earned through the 'Daily Surprise'. As the name implies money is given out once a day and if you decorate the amount that you receive is increased.
Easy Cash
Have 18 worker bunnies and make them dig french fries. Then go to 'Settings' and tap 'General' followed by 'Date and Time' and change it to one day forward. When you return to the game your french fries will be ready.
Stolen
Remember to collect the food in time otherwise it will get stolen. Use the 'Push Notifications' feature to remind you when food is ready to be collected.