Throughout the movie, Otto's broken leg switches from left side to right.
At the Archery tournament, Little John has been wearing his Duke of Chutney clothes to fool Prince John. When Robin Hood, Maid Marian and Little John are running away after the fight, Little John suddenly has his outlaw clothes on. But when he reappears to grab Lady Kluck into the forest, he's back in his duke clothes again.
When Robin Hood and Little John (both disguised as stereotypical medieval fortune tellers) are allowed to kiss Prince John's hands, Robin is seen slyly slipping off one of the Prince's rings before kissing one of his hand, while Little John kisses off the stones from the Prince's rings on his other hand. In the next scene however, you see Prince John still has rings (sans stones) on both his hands.
During the 'fortune telling' scenes in the beginning of the film, Prince John's crown changes from having all red jewels to having red and green jewels numerous times.
When Robin and Little John are on the side of the road posing as gypsies to attract Prince John and his patrol: in one shot, when they are bowing, Robin is barefoot; in the next shot, his shoes are back on.
Historical inaccuracies inherent to most versions of the Robin Hood legend. In the movie, Prince John is shown raising taxes on the poor people. In reality, Prince/King John Lackland was notorious for raising taxes on the nobility. Similarly, King Richard is depicted as a loving king who guards England dearly, when in reality he spent all of his short leisure time at his French estate, and once said he'd sell London to the highest bidder if he could just find a buyer.
When Sir Hiss's head is inside the balloon, he inflates it by blowing into it. Since he is inside the balloon and therefore using the air also inside it already, he wouldn't make any progress. Furthermore, the air he was breathing out would've been mostly carbon dioxide, which is heavier than air and thus wouldn't have made him float. Also, he would suffocate as the oxygen depleted.
Prince John appears to be a female lion (no mane). There are numerous causes, such as chemical imbalance, that can cause male lions to be without manes.
At the beginning of the film, the town of "Derby" is spelled incorrectly as "Darby" on the map. Both spellings were considered acceptable until "Derby" was officially adopted in the 1700s.
When the Sheriff walks up the street towards the well, the star on his costume is to the left, and the feather on his cap points the same way. In the next shot, the Sheriff walks past the well and his character is inverted; to save animation time.
After the jailbreak, a number of reaction shots for which the shot background is the villagers in the speeding wagon, not only do they not "bounce" with the wagon, they are not even animated.
Maid Marian and Lady Cluck are playing Badminton, a sport not invented until the mid 1700s.
Skippy the rabbit child is overjoyed at receiving a "whole farthing" for his birthday. King Richard I reigned from 1189 to 1199 - while farthing coins were produced for the first time in the reign of King Edward I (1272-1307).
At Skippy's birthday party, the children sing "Happy Birthday" to him, which was not written until the 19th century.
Balloons are seen at the archery competition, and Sir Hiss flies around in one to spy on the contestants. However, modern balloons like those seen in the film weren't invented until the 19th century.
When in prison Friar Tuck says " Praise the Lord and pass the Tax Rebate". The first tax rebate in England wasn't until 1799.
At Skippy's birthday party, all of the children are heard laughing and singing "Happy Birthday", but when they show the children dancing around, none of their mouths are moving while they are singing.
When Hiss slaps Robin's hand in the royal coach, Robin says "Now what?" But his mouth doesn't move. Also, Prince John clearly mouths something with no audio. Oddly, this exchange's audio is fixed in some foreign language dubs.
Near the end of "Love," as Robin and Marian finish their romantic moment and are just about to join the rest of the Sherwood Forest gang for "The Phony King of England," there is a touching moment where they walk through a cave beneath a flowing waterfall. On the other side, they emerge... on flat ground, with absolutely no river in sight.
When Robin and Little John are robbing the royal coach, the rhinos guarding it don't appear to notice the 'woman' with a sword approaching, nor do they even notice when the 'woman' is standing under the money chest breaking into it right in front of them.
At one point during Skippy's birthday party, his many rabbit siblings completely disappear from the scene with no explanation, but also aren't shown following Skippy, Toby and the others out of the house.
During the puppet show, they say Prince John is "too late to be known as John the First" if he becomes king. In history, John did become England's first King John in 1199, and as of 2024 is the only English king to be named John. This may merely be poetic license to rhyme with "He's sure to be known as John the Worst," but poetic license doesn't make it any less inaccurate.
When Robin Hood reaches the final of the archery tournament he is referred to as 'The spindly legged stork from Devonshire', but he portrays the disguise with more of a London accent than a West Country one.