Here's what I don't get, why such a rush job on the body disposal? Hell, they could have taken 5 hours to clean out the bank accounts before taking the body out. Then straight to Mexico - don't wait around to see if the cops can figure out if it's your car or not (VIN #'s must be a new concept to Craig).
My guess some or all involved were on drugs - making their sense of time altered. That, paired with just a plain lack of common sense, got them...
My guess is that a phone call log would show some calls to Mass - and the police found that a place to wait for him...