I was in Disneyland on holiday in March. The Cannon in the town square is definitely a breech loading Hotchkiss. I have a closeup photo of the name plate. The cannon at Frontierland is on a Paulson Bros metal carriage but although I remember doing a couple of closeups of the breech end I cannot find it. The memory I have is that it was also marked Hotchkiss, but cannot remember for sure. I feel if it had been marked in any way as a Wiard I would have gotten very excited. Either way the cannon is real and not a mock up. The Columbia was closed to tourists the day I was there so I cannot confirm the existence of a cannon there.
Just an aside, another place in California that I found cannons that is not usually mentioned is the Hearst Castle. I saw a 10 inch (approx) Bronze Spanish Mortar and a Bronze cannon, also Spanish, similar to the longer guns at the Presidio entrance to the Officer's Club. The tour was really tight and I could not break away to take closeups though.
I must say I was disappointed with the lack of knowledge about their cannons displayed by National Parks personnel at the Presidio but the people at Fort Point turned out to be real enthusiasts and I spent a great afternoon with them exploring, measuring and photographing their cannons. They were very proud of their exhibits and once I had demonstrated a genuine interest they could not do enough for me. There is also a genuine historic cannon on display at Alcatraz.
Overall a great holiday with regular stops to look at cannons throughout. If there is any interest I can show some of the photos.
kindest regards
Shooter2