Hello,
@Deltakosh BABYLON.RayHelper is not accessible in the playground: http://www.babylonjs-playground.com/#KNE0O#15
@getzel the demos playground in the tutorial no longer works (with ray.show() deprecated: see: https://github.com/BabylonJS/Babylon.js/blob/master/dist/preview release/what's new.md#breaking-changes)
error : http://doc.babylonjs.com/tutorials/raycasts