All hotels have local Hospitals and Medical Needs phone numbers in their directories.
There is UCI Med Center (Orange) and Kaiser Medical Centers (East La Palma) within a few miles of Disneyland. (Did this handout have this data?)
So, did you call/write Disney and simply tell them that they need to update the data, I'm sure they'd correct this as soon as they're notified. (oops... I see you did... good, but I recommend to not complain to them, but informing them).
Trust me, it's not easy sometimes to keep this data up-to-date, and if nobody informs them, it might not get updated. Medical Offices used to be quite stable, but with the economy, and with law and insurance changes, many have been shutting up, and many doctors leaving to go work for a medical system like UCI and Kaiser.