May be the four way stop was a barrier between the Magical world and the Muggle world and all cars vanished from ther, so no car collide. (reference- Harry potter Series) gr8...!!
Or
May be they gone through The 'Converging point'.. (Please see Movie Thor-2) WoW..!!
and finally...
May be they gone through the four way stop surrounded by the pillars creating a space bridge, of course installed by Sentinal..and They Landed on the dark side of the Moon... Awesome.. (C'Mon.. Haven't you guys seen -Transformers -3)