Continuity mistake: The pony pulling Ditchwater Sal's cart changes throughout the movie. This would be so as to not overwork any one animal. It is most noticeable in the scene when Una is driving the cart after Yvaine. When she is in the city, the pony has a white stripe all the way down its face; when it is galloping in the forest, it has two separate white spots on its face; and the pony that Tristan detaches from the cart and rides has one spot on its face. Also when Tristan detaches the pony, it only has on riding gear (a saddle and bridle), whereas earlier in the scene it only has on a harness for pulling the cart.
Continuity mistake: When the Old Man who guards the wall whacks Tristan to the ground with his staff, the long shot shows him turn it upside down in a threatening gesture, but in the close-up immediately afterwards it's the right way up. (00:23:20)