From one of my Walt Disney books:
When an Imagineer informed Walt that something he wanted to build was going to cost a million dollars, he replied, "When are you going to learn to stop bothering me with unimportant details?!"
Walt often wore the "Wounded Bear Suit." This meant he was in a horrible mood and the staff avoided him until he cheered up.
His favorite drink was a Scotch Mist which he usually had after working hours, but he vehemently opposed alcohol in his park because he felt it attracted a rowdy crowd.
He had to get daily treatments from the stidio nurse in order to relieve the chronic pain in his neck from a polo injury.
He ordered the Matterhorn and 20k Leagues built while Roy was away so he wouldn't be able to try to talk Walt out of it.
Roy did not want to buy the company plane so Walt convinced him to navigate on a scouting trip to WDW (Roy was a navigator in WWII). After the trip, Roy approved of the plane.
Disney World was renamed Walt Disney World by Roy in Walt's honor.
Lillian remarried after Walt's death.
His cough was legendary and warned everyone he was coming.
WDW is based on memories of Marceline Missouri where he lived as a child, although he was born in Chicago.
The house he bought his parents had a faulty furnace. His mother died from carbon monoxide poisoning in the house and it nearly killed his father. He refused to speak about it for the rest of his life from the guilt.
He was a staunch anti-communist.
His summer home was called "Smoke Tree Ranch."