The checkpoint at Fal is on the east side of the road to catch traffic coming from the south.
If he were traveling south there is no checkpoint on the west side of the road.
You are right that the check point is on the east side of the road. He made the u-turn on the west side of the highway. He was spotted by the BP making the turn and that is the reason they went after him. KURV was amazed at this too. There is only a little picnic park that separates the highway and you can see from one side to the other.