pjadedd wrote:
I think it has to do with time lost from misreading the clue. The typical penalty seems to be 30 min. My guess is that if it would be more than 30 minutes, they give them that penalty. Also, they only let the teams go back when it's walking to the pit-stop (minus Heave). I think when the nerds made a mistake, it was in the middle of the leg.
That's how I figured it.

For the nerd guys, it was in the middle of the leg and it would have been farther for them to travel back to the starting point of where they first got in the cab.