I've got an Xbox debug kit with Forza on it, it has a debug menu, I'm unaware if this is something common or not. Is there any interest in this? I'll try to get a video up and maybe a build number if I can fine one once I'm home. EDIT: I'm not sure I meant to post this in the unreleased games (as the retail game is released) forum ... maybe the xbox 1 forum would have made more sense
I don't know much about this game but the best you could do is check the file dates if you can't find a build number, it'll help tell how early or late the build is.