Ok, the movie is a follow-up of the initial set ten years later. The backdrop is supposedly the admission of California to the Union. In and of itself this was a potentially decent backdrop for a movie. However this was about where the history ends.
Our first glaring inaccuracy appears in the first scene where a villain attacks people with a Henry rifle (against which everyone is using muzzle loaders) and brags about it. Of course the Henry Rifle wasn't invented till 1862. The use of the time machine in getting this future weapon was not mentioned. [Now keep in mind, I'm a gun nut so this stands out, but this is only a small fraction of the avalanche of historical garbage. I don't even remember all of it]. Had the writer just claimed it was a volcanic rifle, they would have been closer by using the first repeating lever action rifle, but that arrived in 1856.
So the bad guy has a superior weapon which doesn't exist yet as his rifle, and still uses flintlock pistols even though revolvers are commonplace at this time. In fact we don't see any revolvers in this movie, which really is bizarre.
But that's just technical whining, which probably bugs me unduly.
Let's get to the 'plot'. The plot is that the Pinkertons (which was in reality a private security agency founded in 1850, and had no government connection until the civil war when Pinkerton worked for the Union) convince Elena to divorce Alejandro (after they had a spat based on him being Zorro) so she can gain the confidence of a French Count who is up to nefarious things in California. They happened to see Zorro without his mask and used this for leverage to get her to do their will.
The count is, of course, a member of a one-world secret organization (Orbis Unem). This organization is supposed to be a bunch of aristocrats who are the power behind all the thrones of Europe. They fear the U.S. becoming a world power and thus plot its downfall. This organization is so secret and powerful that they even have their own soap label (I kid you not).
Their nefarious plot is to use their private label soap to make nitro glycerin and then give this powerful explosive to the Confederacy to start a civil war and thus break up the U.S. before it is able to become a world power. Of course the fact that nitro glycerine is too unstable to be militarily useful, and that the Confederacy wasn't even vaguely conceptualized yet won't get in the way of this brilliant scheme.
After a series of off and on again accents from various characters (particularly annoying was the Padre with the Bronx accent when he wasn't trying to do Mexican) Zorro and Elena do break up the plot with the aid of their kid (ten year old).
There is plenty of action, but the quality is not comparable to the first movie. The characters picked up a fighting style where the swords were a mere ancillary to their kung fu-ish moves. Everybody and their cousin was a trained gymnast, though Zorro in particular seemed to think a standing back flip was a good move especially when fully unnecessary. Though I admit the kid was a close second, winning the silver for gymnastics (Elena for the bronze).