While Paige is talking with Lady Godiva, and looking through the history book Paige moves her hair behind her right ear. In the next shot her hair is not behind her ear anymore.
When Phoebe rides a horse to the café in the nude, her prominent tattoos are absent in all shots from behind, revealing it to be a stunt/body double.
When Leslie is inspired at the end and starts to type on the computer, it is obvious that he isn't actually typing anything, just hitting a few keys on the keyboard.
When Leo recoils from the flying debris of the demon's explosion, it's obvious that the 'debris' is just a handful of round clear glass pebbles, being gently tossed at the actor by someone off camera.
Godiva is the Latinised version of the heroine's actual name, which is Godgifu/Godgyfu, meaning "gift of God". She would not have referred to herself as Godiva.
Paige states that the sisters can't summon Lady Godiva without the spell created by Duncan. But there is no reason given for this. The sisters were able to send Godiva back to her time with their own spell, so they should be able to summon her too.
Paige tells the elders that her sisters learned magic from their mother and grandmother. The girls' mother died when they were young, and they didn't learn they were witches until after Grams died when they were in their 20s. Though they have summoned Penny and Patty from time to time, they actually learned the craft largely on their own.