When Zorro is sword fighting Saragoza, in closeups, Saragoza is standing firmly in place and swinging his sword at an off-screen opponent. The background behind him never changes. In the wider shots, Zorro is continually forcing him to step backwards, and even side-to-side, yet the closeups do not reflect any change in his position.
In one scene Diego is comparing the handwriting between two letters, one a letter to him concerning bird-watching and the other is supposed to be a general letter to the de la Vegas demanding a higher tithe to the church. However if you pause on the letters, both are addressed to Diego directly and have the same text about bird-watching, just in different handwriting.