“Oh bother! I just realized if we fly into the buildings while holding our passports, they’ll be able to identify us!” said Terrorist 1

“That’s a good point!” said Terrorist 2 “Here, hand them to me.”

Then he quickly rolled down the window and threw them out, right as the plane impacted the tower, thinking he had committed the perfect crime.

“That’s our story and we’re sticking to it. Now go to bed.” (not really, I don’t know what the official explanation actually is)