Quoted from colonel_caverne:
Don’t know what happened. Was in tunnel mode, completed a round, hit another White arrow and I see on the Screen 70M, another shot, 10M..
I think I succeded 3 or 4 tunnel shots before starting the first white arrows set.
Shooting the Railroad shot between the Arena ramp and the well walker starts Tunnel mode. Tunnel mode consists of two phases.
In the first build phase, all lit shots including Tunnel are worth 5M. However, shooting the Tunnel before making any of the other lit shots increases the value of all shots, including tunnel, by 2.5M per shot. Shooting any other shot will lock in the value of tunnel. In the second collect phase, all shots are lit to collect whatever value was built in the initial phase of Tunnel. To finish Tunnel mode shoot the Tunnel shot after collecting any other lit shot."
My guess is you hit tunnel again at the beginning to award ten million per shot instead of five. Then you got into the second collect phase and it awarded you the value that you built in phase one.
It's not clear to me how to get to the second collect phase. If you shoot tunnel again the mode ends. Maybe shooting barn, CDC, riot, and arena, then they all relight?