Happy Election day! ;)
As for the historical correctness: I truely don't know what the hall where the trial took place exactly looked like. There are, however, some contemporary paintings (by Lucas Cranach e.g.) that show the scene but they differ and they tend to glorify Luther as the paintings weren't done for pure enjoyment of painting but for political purposes.
The core of my scene is correct, though: The desk with the books in the middle, the emperor sitting on a throne under a canopy, the princes (electors), the audience. The red carpet I borrowed from a painting by Titian that shows Charles V. some years after the Diet of Worms.
The tiles on the desk are stickered, they are from some Homemaker sets (70s), I don't know which ones because I only got the tiles singly. The thing on top of the crown is a small Belvile crown as TheBorok already pointed out.
Formendacil, may I - offtopically - ask why you like Charles V.? Because he waged war all the time, or because he plundered Rome although he considered himself the preserver of Christendom?
As for Luther splitting up the Church: Right, but if he had been a bishop or even cardinal rather than a little monk we would possibly be still all catholics now :-) At least the pope (Leo X.) didn't have the power to prevent the schism. Like others before him didn't have the pover to prevent the schism between the Roman Church and the Greek Church.
This is just the sort of nonsense up with which I will not put.