Asshat arrives at the location where the box is supposed to be, and they see it right away. They stop the cab and get out. They grab the clue, and it's a Roadblock. As Phil explains, in this Roadblock, one person has to drive a bicycle taxi with the other person in it along a marked course. The course ends at a ferry boat, and they have to get on the ferry and go across the river. On the other side of the river, there's a place to park the bike, and then you run to the pit stop at the Café Thu Thiem.
When Asshat reads the clue, which says that the person who does the Roadblock should have "strong legs and a strong back," Ian reluctantly agrees to do it. Once he gets on board, though, he's relatively good at it. He pedals Teri along the street with little difficulty.
Ken and Gerard, meanwhile, are stuck in traffic.
Asshat makes it to the ferry. "Woooo!" they yell. "You numba one!" Ian yells at some more people on the ferry. Yeesh. In an interview that plays as he and Teri cross the river, Ian says that it's the first time he's been in Vietnam since the war ended, and he says he likes it. "I like the culture, I like the people." Which is nice. And if he stopped barking "numba one!" at them, I would think it was even nicer. He says "over time, the wounds will heal." Yeah. I agree. But still? That's a big no on calling people "numba-one taxi drivah."
Derek and Drew drive in their taxi past where the route marker is located. It appears from the way it's shown that when you drive to the actual address on the clue, that takes you to the area where the course is, but not right to where the clue box is, which I think is the cause of the problems here. When Derek and Drew hop out of their cab, it's actually because they see the yellow flag at the ferry at the end of the cyclo course, so they have problems already. They talk, in fact, about having seen the little yellow flags that mark the course. Of course, this would make you wonder why they didn't figure that perhaps this might be the wrong end of the course. They look around, and they show the address to people, and they are led in various directions. "This is so frustrating," they remark.
Teri and Ian, on the other hand, don't find it frustrating at all. They get off the ferry and are very near the pit stop.
The Bald Snark appears to get out of their cab right where Derek and Drew did -- where they see the yellow flag that leads them onto the ferry. So now they and the twins are running all over the place looking for the green box.