Numero quatro: When it dawned on the Hoover family as they drove along in their van that, well, someone was from the group wasn't there.
FROM THE SCRIPT:
Richard:
"Let's go!!"
Furious, Sheryl goes and gets in the bus, slamming the door.
Everyone else gets in. Richard releases the brake and they drift down the hill.
As the van rolls away, Richard shifts and GUNS the engine.
Silence. Everyone avoids everyone else's eyes. Finally, Franks glances around.
Frank:
"Where's Olive?"
...And so they circle back and load her in -- without stopping, of course.
As Uncle Frank would later declare, "No one gets left behind!'"
Indeed -- in this movie no one did.

Paul dano is amazing