Signs of people that have disappeared are everywhere in the beginning of the movie. But it seems that they took their clothes with them, but left cars and other things that surrounded them. The exception are babies, who left even their blankets and supposedly left naked.
The crew was very careful during takes to not to film any activity in the background of scenes that would spoil the illusion of there being nothing living left on Earth. So much so that the assistant director would constantly stare at the background where ever the lens was pointing during takes to ensure nothing was inadvertently caught. However as mentioned a car can be seen in the far distance in the scene just before Zac goes into the church and again at about 1hr 3m 03sec when Api and Joanne are jogging down a foggy hill.....a white car can clearly be seen driving past in the top right of the frame.
When Zac is driving the big earth moving machine (at around 33 mins), just as he stops, if you look through the window of the truck in the upper left of the screen you can see a car passing in the distance.