With so much fun minutia recorded in Herodotus, I had to pick and choose what I included. =( But hey, in case you’re interested . . . here are a few of the many stories I opted to leave out.
At one point, Xerxes rests under the shade of tree that so pleases him, he adorns it with golden ornaments and leaves Immortals behind to guard it. I so wanted to find a way to weave that in, but alas. =)
Demaratus (exiled Spartan king) supposedly sent a message of warning to the 
Spartans (more to gloat than to warn, really) in a really clever way. See, he took a typical message tablet—hinged wooden box that opens kinda like a book; inside are two wax surfaces, on which the message is pressed with a stylus. Close it up, and voila–your message is protected for the journey. But not exactly secure. Damaratus, though, did something never before recorded. He peeled off the wax and scratched his true message into the wood, then put the wax back on and pressed a benign one into the wax.
Of course, his peeps back in Sparta had no clue why exiled-dude was writing them with something so useless and thought long and hard on it until finally someone said, “Hey, let’s look underneath the wax.” Took them months to figure this out, apparently.
This was such a fun story, but there was absolutely no way I could work it into Jewel of Persia. So I stole it instead. 
I took the cleverness of the idea and made it the standard way two of my bad guys communicate when they’re apart.
Gotta love poetic license.
There were a couple instances where storms played huge roles in the war. I mentioned a few, but there was one huge one where 400 ships from the fleet were destroyed. It raged for three days and nights, finally calming after the magi did their magical thing. I wanted to have it instead be a result of my heroine’s prayers, but as it turned out, I left it out altogether.
When Xerxes arrived in a place renowned for its fast horses, he pitted his own in a race—and won so handily it was anticlimactic. =)
When they arrived at the canal, it was when the man who had been in charge of construction had just passed away. This man, Artachaus, was supposedly the tallest man alive, and had a voice so loud it could be heard for miles. Upon his death, his people instituted a hero-cult in his honor.
After coming through the canal, they went through a mountain pass populated by lions. Each night the lions would come down and attack . . . the camels the Egyptians brought. Nothing else, mind you, just the camels—the one creature they wouldn’t have been familiar with.
There’s more. But I won’t bore you. =)