I did this by accident before, at a 5K. I arrived to the race so late that when I crossed the starting line to BEGIN the race it registered that as my finish time and I'm posted on the result website as finishing in 2nd place.
Accidentally registering a false time (even accidentally cutting the course and claiming a prize, which would be more than you did) is very different to cutting the course and then cycling the route to falsify GPS records.
