I work as a volunteer to help prepare people at my work for quakes, and having heard presentations/panels with Disney personnel on them - the parks are well prepared. Rides automatically shut down and are inspected, as others have noted. Most if not all the buildings at DLR are fully retrofitted to current seismic codes. They have enough food, water and sanitary supplies on hand to handle guests for at least three days, plus all kinds of other detailed plans, because if freeway bridges are down people might not be able to reach home safely.
There is a major hospital/trauma center - UCI medical center - less than 10 minutes from the park.
I can think of WAAAAY worse places to be when the big one hits than DLR.