Well, when you see the picture of the Saudis, they could be in their late teens. And the detail with the black raincoat makes me think they were trying to look like kids (many of the "goth" kids feature black raincoats as their school gear). Also, the driver was a substitute who didn't know the kids.
Just posted a response to ElGato answering similar thoughts. See post #40.
Sounds like you too are intrigued by the fact that they entered on the sub's day...