The light in the window above the firehouse- it used to be on only when Walt himself was in the park. He died of lung cancer in that apartment and his final resting place is Forest Oaks.
I still think I saw him once as a child, standing near the trash cans outside of the Jungle Cruise, but now I am OT. It is lit at all times now to symbolize that Walt's spirit is still always in the park. There are several behind the sceens tours offered at DL, well worth it if you like that sort of thing and have time.
When you walk into the park it is like a theater, walking under the rail station and coming out onto Main Street is like the curtian opening... The heights of the false fronts on MS make you fell like it is longer when you enter the park and shorter on the way out. Think about the names/words on all the shops- they all have some special meaning, some are obviouse some not.
There is at least one hidden Mickey on each ride, 'extra' hidden Mickey's in the Haunted Mansion are a running joke.
Don't miss the Gallery over Pirates, it is great. The POC was Walt's favorite ride.
Among the opening stars 50 years ago were Art Linkletter, Bob Cummings and Ronald Reagan, Frank Sinatra, Sammy Davis Jr., Jerry Lewis, Danny Thomas and Irene Dunne.
Is this the kind of stuff you were looking for? If you want park touring tips I can see if I can dig up an old post where I gave a detailed touring plan... it is slightly out of date but the basics are still the same (some fast pass rides are no longer fp rides and Astro Blast was not there yet).