As an attorney for a large manufacturing company, I regularly deal with Prop 65 issues. I've never seen a sign like this though. How can the "Disneyland Resort" contain the chemicals? Are they referring to the materials used in the physical structure? Fumes released into the air by certain rides? I would almost think this sign was a joke except that I'm sure that Disney would not post it if they were not required to do so. Strange.
I never touch the bat stanchions in Haunted Mansion because I heard they contain lead. Of course, I would never touch them anyway so as not to disturb anything sacred, so what does it matter.