I checked out Wikpedia, which says: Penalties and time credits
The standard penalty for minor rule infractions is 30 minutes plus the time advantage gained (if any) by disobeying the rule. This penalty is known to apply in the following cases:
Using a prohibited form of transportation. For example, a team that takes a taxi when the clue specifies that they must walk would receive a penalty (Frank & Margarita and Joe & Bill, Season 1; Heather & Eve, Season 3; Reichen & Chip, Season 4) or to take a bus to a destination, when the clue specifies to take a train (BJ & Tyler, Ray & Yolanda, Season 9; Lake & Michelle also took the bus, but were not assessed the penalty, due to arriving last at the pit stop). The penalty was revised to 15 minutes in Season 9.
In this case, I'm not sure if they reverted back to a 30 min penalty - or if it was a 15 minute penatly plus 15 mins for time gained.