Just before the end of the second match, after Olaf hits Arthur with the mace, there's a shot where the prop can be clearly seen to have broken, leaving him with just a handle and chain. A few seconds later, he's holding an unbroken mace, and prepares to strike Arthur with it.
Uther states that during Olaf's challenge against Arthur, they will fight in 3 rounds: quarterstaff, mace and sword. However, the weapon used in the second round is not a mace, It is called a flail. A flail has a spiked ball at the end of a chain, while a mace is a blunt weapon with a heavy head on the end of a handle.
In the first image of the castle Camelot, a jet's contrail in the sky is visible.