I have a feeling Mark and Bopper are way, way, behind. So far behind in fact, that if they do get to go for the Fast Forward (assuming there is one), it might not be enough. And it is possible that the Fast Forward won't be available for them until after the Speed Bump. Dave and Rachel not only finished the roadblock ahead of the other teams, they finished the detour ahead of the other teams, and I suspect before any of the other teams reached the detour.
While we can't conclude logically that Mark and Bopper are eliminated this leg based on what we've seen so far from CBS, I seriously doubt they'll win the leg. There's also a suspicion in my mind that we may see a team fall seriously behind on the leg in Japan, and I'm wondering if this may possibly explain the two-hour finale, rather than two separate episodes. It hasn't happened in a long time for a fourth place team, but the way this season keeps giving us callbacks to earlier seasons, it wouldn't surprise me at this point.