Here's my video walkthrough of Act 3, complete with this achievement:
1. When on the Zero, find the bureau (if you wait, you can click the ZZZ in the bottom left).
2. When you find the Bureau, drive counter clockwise (about two laps for me).
3. You'll reach the TV. Stop, slowly move the other direction (clockwise) and you'll see The Van. Go here.
4. As the dog, walk to the far left of the van. You'll see Phil and Jane up on the hill.
5. Achievement unlocked! Feel free to leave!