Revealing mistake: During the shoot out with McGivens's gang at the Cortez ranch, the wife of Cortez sneaks out of the trap door with her baby and peers around the side of the building. You can notice that the baby is really a doll.
Revealing mistake: In the burning barn, watch closely when Zorro goes to jump on the horse. There's a low angle shot of his feet running up to the horse, and a piece of burning wood lands in the foreground. The fire on top of the burning wood is burning upwards like normal fire. However, the fire on the side of the board is somehow burning upside-down, with the fire moving downwards. Seems to be a slip-up in the digitally-added fire effect. It goes by quick, so slow-motion helps, but is not required.
Revealing mistake: Watch closely when Zorro's horse bursts into the burning barn. The visual effect is comical. It, along with some debris in the air, simply appears between frames in an unrealistic way.
Answer: Compromised means that her cover was blown.
Myridon