First of all, I know that EU isn't canon, and GL can write whatever he wants, etc, etc. This is just for fun.

I noticed the following things were mentioned first in the Heir to the Empire, then in TPM. Whther GL told him to put these things in or what have you, doesn't really matter:

-The planet Coruscant
-Palpatine being a senator
-Jedi all wearing the same kind of robes
-The old Republic
-Some others I can't remember right now

So, considering these little tidbits were right, perhaps some of the information on the clone wars is correct, also? Most of the EU steers clear of anything relating to the prequels, but the trilogy mentions that clones had the habit of being insane and unstable. It also talks about "clonemasters". It will be interesting to see to what extent Episode II agrees with the Zahn trilogy, eh?