It has to be so that the end of the train that is attached to the tractor is open? I doubt that a bit, firstly it will probably be a little windy and cold and secondly because of safety.
you always sound like a DTG apologist, even though an end door might be left open occasionally, I really doubt this is company practice, unless on empty stock moves. no railroad will want to encourage 'train surfers' this way. and when MBTA finds out their safety rules are violated by some gaming studio, it could mean end of license even.
Are these the same Americans who put bars on the first floor windows of the Allied apartments in Berlin, out of concern that their children might fall out?