Hi guys! Based on everything that the press released, even saying that there would be new twists even before this episode, I think of the following
First placer team experiencing dead last - that more or less must have been Margie/Luke, we see Luke struggle so much in the Roadblock, that must have been them, further, I think that the roadblock itself is a first come first served basis, that is why they suffer being last.
And the new twist is not actually new, rather somehow, a modified version of the u-turn where the first team who reaches the u turn marker is forced to make a mandatory u-turn of another, and that they must randomly pick only one team... I may be wrong and it would actually be like K/V u turning N/D in Season 12, or in TARAsia3, G/T u-turning AD/F not because they hate them, rather to gain time...
The new twist may actually be a new twist?... We'll all find out next week...