Hi, have you really played the game? Ok, I guess I think that to make invisible barriers disappear, is to have 3500 points of start before entering the time section, destroying all the bricks and collect all net-points possible (the yellow cubes) very fast, kill the infected terra-qubiters with fireball & avoid the hopping blocks on their path (that to kill them you have to a very good precision).
I plan to review the part of the countdown with a clear objective, and you can also zoom with the mouse wheel to get a better view.