- Myth: The Mexican Government gave Guillermo Castro Rancho San Lorenzo because he was a loyal soldier. Reality: It was not nearly that straightforward and required 6 long years of pleading, negotiating, and a whole lot of backstabbing!
- Myth: While rogue settlers were setting up homes illegally over in Squattersville on the Estudillo's Rancho San Leandro, the honest settlers in Castro Valley bought their land from Castro. Reality: Castro was fighting as many as 80 squatters on his rancho.
- Myth: Castro's Rancho San Lorenzo was auctioned off at high-noon on the San Leandro courthouse steps in February of 1864 for $400,000. Reality: This appears to have been a fanciful fabrication created out of thin air in 1969 by an East Bay Regional Park District PR man to build the hype around the opening of Don Castro Reservoir and Park--or was it?
- Myth: The first school in Castro Valley was on Redwood Road at Alma Avenue, as commemorated in 1962 by placing California Historical Marker #776. Reality: Depending on how you count, it was either the 2nd or the 6th school to serve the greater Castro Valley community. Almost all of the story used to justify the commemorative plaque seems to have been little more than Brickell family lore, and almost all of it is demonstrably incorrect.