1) The autorrect behaviour happens just if you use the DateTimeInput of the Mvc Controls Toolkit: http://mvccontrolstoolkit.codeplex.com/wikipage?title=DateTimeInput%20and%20DateRange%20attribute otherwise, normal unobtrusive validation is performed and when the field is invalid the usual validation message is shown.

2) For everything to work properly you have to install the Mvc Controls Toolkit since it has custom Validation and Metadata provider. It is available throught Nuget (Mvc3ControlsToolkit or Mvc2ControlsToolkit), or you can install it manually as explained here: http://mvccontrolstoolkit.codeplex.com/wikipage?title=Installation