Over the months I have been in possession of my copy of THE ESSENTIAL BATMAN ENCYCLOPEDIA, I have noticed several errors. The first is in the entry for Jaffeer, the man murdered for his ruby by four criminals who all die in the manner Jaffeer predicted. The last one to fall, a man called Mortimer "Brains" Brynig, is said in the encyclopedia to have died by drowning when in fact, according to the original version at least, he died of thirst.
The second lies in the entry for Paul Sloane, the actor who comes to believe he is Two-Face in his original Golden Age incarnation. The entry relates that he was injured when a klieg light explodes and this is true only in the reprinted version: in the original version, the vial used in the movie contains acid put there by a jealous prop man.