The incorrect piece of information is:
"The spot marked 'maximum gravitational potential energy' should be on the lowest point of the roller coaster, at the far left side on the bottom."
Why it is wrong: At the lowest point of the roller coaster, the gravitational potential energy is at its minimum because potential energy is highest when the roller coaster is at its highest point. At the lowest point, the roller coaster's energy is primarily kinetic energy, not potential energy. Therefore, the maximum gravitational potential energy occurs at the highest point of the track, not the lowest point.