We have tested what is shown in the report and have found that it is possible. We suspect that some walls in the game can physically stop people and cars but allow bullets to travel through at a long distance.
In the video below, we have tested the exact scenario in the report. I was in a kart, at the top of the parking lot, and Quido was surfing on Rep’s bike. As you can see from our video, it is entirely possible. However, it was also possible for Quido to shoot me without surfing on a vehicle and I could also be hit without being inside a vehicle. Hence, the conclusion is that some walls allow bullets to travel through at a long distance.