If you travel back in time to January 1st, -4715 and continue to travel backward through time, the Month/Day/Time display will begin to display incorrect data.
First it begins counting the time for January 0 -4715, then it starts displaying the month 0. Once we go through that month, the year changes to -4716, but the months continue to count backward all the way to -8. Upon completing the month of -8, the display correctly shows February 28th ( or 29th? ) and is correct all the way to January 1st, where the negative display begins again.
The time of day is also displayed as a negative number at times, although I didn't slow down to watch how it behaved. It was possible to have a display of -4716 -6 -11 -5:-23:-11.
Have fun!