When Zorro and Valasquez ride into the tree branch and are knocked off their horses, they lose their swords. When the get back up, their swords are in their hands
The Wanted poster that Esteban has made up of Zorro shows the top half of Zorro's face with the lower half covered, like a bandit. But Zorro has always been seen with a keyhole mask, covering the top half of his face, while exposing the bottom half.
At the climactic fight, Zorro dramatically thrusts his sheathed sword into the hands of the enemy. Yet when he is released by his brother, he draws his sheathed sword from where it is belted around his waist.
A moment after Esteban smashes the bowl of green apples in Don Diego's bedroom, the bowl re-appears, undamaged.
Don Diego and Esteban encounter Bunny, who's in the guise of a priest. Esteban asks the priest for a blessing. Bunny has them repeat after him, but when he says the line "Oh Heavenly Peter...he who sews and knits.." Don Diego and Esteban repeat the line as "...he who knits and sews..."
During the costume ball fight scene when Zorro slices the Alcades belt to let his pants all down, there is a large slit in the left side of the pants.
When Zorro kisses Charlotte Taylor Wilson and she faints, George Hamilton says Lauren Hutton before he splashes water on her face.
When Zorro uses a bull whip to cut his name in the wall, he needed 13 strokes of the whip to do it. Only ten cracks of the whip are heard.
Don Diego and Esteban call each other childhood friends, so it's unbelievable for Esteban to not know Diego has a twin brother.