There is a small programming mistake, when you ring the phone to distract the guard, he goes one space right and then up, but if you keep ringing the phone, he keeps doing this until he crashes into the desk, and the game freezes because it can't complete the animation.
Yes!! You might be the first person to actively point this out, haha. It was very much intended, since Future Todd's character was inspired by Biff. More details in this Facebook post: http://tinyurl.com/yarn8cxv
Thanks