Factual error: In the show Gaius wears glasses, except eyeglasses first came into use in the late 13th century while the legend of King Arthur is around the 5th or 6th century.
Triumvirate of Terror! - S3-E8
Factual error: During the final fight in Lex's lair, Joker gives Batman a good smack with his large hammer. As is common in this show, when a good hit is delivered, a freeze frame is show with the figures moving in slow motion with a stylized colorful backdrop to add to the drama dynamics. But as Joker delivers this hit and this stylized shot is shown, the show cuts to some inmates in a prison cell watching the fight on TV. The same stylized shot is shown on their TV, where it would be show like that there, only to us. They would have just seen Joker hit Batman with the hammer and him fly off in real time with no stylized back drop or slow mo. (00:20:00)