It's not entirely true that you have to add .json - at least not from my experience when I have switched from 1.0.x to 1.1.x.
In order to make Rails app return json without specyfing extension in URL for Angular 1.1.x you need to make angular add additional header to http request:
myModule.config(['$httpProvider', function ($httpProvider) { $httpProvider.defaults.headers.common['X-Requested-With'] = 'XMLHttpRequest'; }]);
Without that Rails by default renders whole HTML instead of returning JSON.