There may or may not be a barrier on the inner part of the course. According to your example (assuming you could go on the inside of the course), you would 25+25+25+50. So, 125 points. You would get no time points, because those are based on a successful run, which this was not. You would only get bonus points. So, someone who completed the course without the hoop in 4.5 minutes would have more points.
A ground vehicle cannot be DQd for going in or outside of the course. The only 'limits' you have are time. if you want to just drive straight and keep going until you hit the mountains, go for it. we'll just add up whatever points you got after 5 minutes.