When Glenn and Sgt. Abraham Ford have a fight in the road, there are some shots of Dr. Eugene Porter at the back of the truck. One of the shots is reversed as Dr. Porter is suddenly on the left and facing to the left. The contents and camouflage on the back of the truck also show that the shot is reversed. The next shot of Dr. Porter shows him back on the right side behind the truck, and then he walks to the left.
The claimers would have immediately known someone was in the house, because the couch had been pushed against the front door and the doors and windows were locked.