When Byron and Andrea first appear in bed together, Andrea's lingerie shoulder strap is alternately under her left arm/on her shoulder between shots.
At the book signing near the end of the film, Byron signs the name "Georgette" in the book for the woman named Yasmine. The next woman in line reveals her name to be Georgette.
Byron says that Excalibur is the sword that Arthur pulled from the stone. Excalibur--Arthur's magical sword--was actually given to him by the Lady of the Lake. While it some versions of the story, the sword in the stone is also named Excalibur, it was destroyed shortly after, and was not the magical sword of legend.