When the bad guy tries to attack King Arthur he is repelled by the sword. He runs out of the chamber and slams the heavy wooden doors closed behind him. As he does so three knights throw a spear at him. However on the other side of the doors, seven spears are shown piercing through it.
When Kayley and Garrett are crossing the acid pond on the bobbing rocks in Dragon Country, they show a top view of Garrett crossing and that he only has one rock until he reaches the edge. But then they show you the front view of Garrett crossing and it shows he has several more rocks to go before the edge.
When Garrett is crossing the acid lake he gets almost to the end. However when Kayliegh tells him to hurry, the shot goes back and it shows him back at the start.
In the second-to-the-last shot where King Arthur comes out of the keep after Excalibur is back in the stone, Garret's stick, which had previously been in two pieces in Arthur's projected path, scoots to the right and one piece (the top half) is missing.
When Lionel and the other knights go to Camelot, it takes a day for them to get there. When Arthur and the knights go to his house with his body, it might be implied that it took longer for them go there, as it is already winter.
When Julianna turns to the family painting on the wall, Kaylye's father is depicted as he was right before his death, as is Julianna. Kaylye on the other hand looks like a teenager instead of the small child she would have been when the painting would have been made.
The scenes of the knights repairing Camelot seems wrong they would be more likely to be searching for Excalibur.
Damien, a knight goes to Camelot and takes a shield with him but no sword but he has one when he goes to the round table.
When Excalibur is stolen a horn is blown which is heard 3 days ride away where Kayley lives and people automatically know that the sword's been stolen.
None of the knights wear armour.
At celebrations at the end the peasants do an Irish dance.
During the last part of "On My Father's Wings," (the verse "I will do great things, on my father's wings) Kayley's lips don't move in sync with the song, despite the fact she is singing.
When Devon and Cornwall make shadow puppets on the wall, Garrett (who is supposedly blind), looks at the shadow puppets on the wall.