To me, it looks like 12:25, and after a little research...
-Walt dedicated Disneyland at 4:43pm.
-Walt died at 9:30am.
So either way, the clock does not signify those. I'm willing to bet it's the story reason then, with the castle being frozen. That's not to say that there is another reason as to why they picked 11:35 though. But by the same token, the artist designing the clock could have just looked at the time when it came time to draw the hands and went with whatever it said.