During play, the screen background was solid black with a white
border, with one color line representing each player.  We displayed the
game score in a horizontal strip at the bottom of the screen.  It
wasn’t the most graphically advanced program, but it was simple and
fun.  It looked something like this:

[…]

“Both the AI and the humans had three missiles they could use during
the course of the game. When a missile hit a wall, it would create a
mini ‘explosion’ that would erase the color on the background back to
black as it faded out – thereby eliminating sections of the trail left
by previous cycles.”

Soon we had players and computers firing missiles to shoot their way
out of tight situations. Nonetheless, Tron purists may scoff, since the
movie programs didn’t have such luxuries as missiles to get them out of
a bind.

[…]

One day, when Marco and I were playing against two computer
opponents, we forced one of the AI cycles to trap itself between its
own walls and the bottom game border.  Sensing an impending crash, it
fired a missile, just like it always did whenever it was trapped.  But
this time was different – instead of firing at another trail, it fired
at the game border, which looked like any other light cycle trail as
far as the computer was concerned.  The missile impacted with the
border, leaving a cycle-sized hole, and the computer promptly took the
exit and left the main playing field.  Puzzled, we watched as the cycle
drove through the scoring display at the bottom of the screen.  It
easily avoided the score digits and then drove off the screen
altogether.

Shortly after, the system crashed.

Our minds reeled as we tried to understand what we had just seen. 
The computer had found a way to get out of the game.  When a cycle left
the game screen, it escaped into computer memory – just like in the movie.

Our jaws dropped when we realized what had happened.  (Real Life Tron on an Apple IIgs)