I agree with Pari ji - the book is definitely worth a read!
I've not seen 300... but when I saw the elephant come out, I immeadiately thought that we were going to see a lift from Jodha-Akbar 😆
In the book, there is not much written about Devavrat's time at Hastinapur leading upto King Shantanu becoming mesmoriszed by Satyavati Devi... and so I'm not too surprised that the makers chose to put in a few scenes like that! hehehe.
God bless.