The Regent withdraws the Magna Carta and, when the nobles agree, the Earl of Huntington (the former Robin Hood) vows to fight him and maintain the people's right to rule themselves. In fact, the Magna Carta didn't create a democracy, it was forced upon King John by the nobles to guarantee the rights and establish the political power of the nobles, not the people. The nobles would never have let the Regent withdraw the Magna Carta and strip them of their power.
Queen Eleanor of Aquitaine is shown alive during the minority regency of her grandson Henry III. Eleanor actually died in 1204 during the reign of her son King John.
They make the mistake of calling it The Magna Carter when there is no the in front, it's just Magna Carter.
When Friar Tuck is swimming across the moat, the water makes it obvious that Edgar Buchanan (or is stuntman) is wearing a bald cap.