I'm betting Duhvid and Jeff make the mistake. See my post in the "who's the dumbest" thread for a list of the silly mistakes they've made this race.
And add to it their hopping on the wrong subway in Korea. They were like- "Hey! There's a subway! We can't tell if it's the right one...but...it's leaving! Better get on it, just in case!" Although that's what comes from Southern California's lack of public transportation, i suppose.
I would've expected Jon and Kelly would go for the fast forward, since they would leave 1st and would presumably get the fast forward first. They've been growing on me lately, but if they really get on R&C's case, then...back to the bottom of my list they go! Maybe the building thing is the fast forward.
And I guess Reichen gets in the water and goes for the clue before he knows there's a shark in there? Or what? That teaser was written kinda weird...
AND for penalties- here's how I understand it anyway- teams are set back half an hour PLUS the maximum amount of time they gained by performing a task if they make a mistake (such as driving when it says to walk). If teams fail to complete a task, they are given a 24-hour penalty (like in TAR 1 in the best episode EVER, when the guidos won the fast forward, then decided to check into a hotel overnight while the other teams went to the pitstop and Nancy & Emily thought they were hopelessly in last place, so skipped the detour, only to find out they would not have been eliminated if only they had completed the task!).