4. Walt had an aggressive timeline

When Roy Disney went out to hunt for investors in 1954, Walt already had a timeline in mind. The earliest promotional material for investors promised, "sometime in 1955, Walt Disney will present for the people of the world — and children of all ages — a new experience in entertainment." Construction on the park began in August of 1954 with a planned opening day of July 17, 1955 — less than a year away.

The summer opening was crucial to the park's success in order to catch summer tourists: if the park opened in the fall, it would sit idle for most of the off-season. And if guests weren't rolling in on opening day, the park would likely be a flop — which would leave Disney in dire financial straits. When the Orange County plumbers and asphalt workers went on strike in the spring, finishing on time seemed like a lost cause and as opening day approached some tough choices had to be made. The of the asphalt was laid only the night before and when faced with the choice of having working toilets or working water fountains for opening day, Walt chose toilets.

5. Opening day WAS a disaster

Everything that could go wrong on opening day went wrong. A limited number of tickets had been given out, but were counterfeited leading to twice the expected number of people coming to the park. The attendance numbers meant traffic jams, shortage of food and drink, and crowded lines (with reports of children being thrown over the crowds to get to the front of the line). Rides broke down under the unexpected onslaught of visitors. Fantasyland had to be closed due to a gas leak. Women's high heels sunk into the freshly poured asphalt. High temperatures — over 100 degrees — sent people looking for water fountains that had yet to be installed. The Mark Twain Riverboat nearly sank because a maximum number of passengers hadn't been established.

The press coverage of the opening — which Walt referred to as "Black Sunday" — wasn't kind. But Walt set to addressing opening day issues and invited the press back for special events where he personally apologized to journalists for their previous experience.

The end result? A million people had come to Disneyland within seven weeks. Attendance figures were 50% higher than predicted and spending was 30% higher than predicted — despite everything, the park was well on its way to becoming a huge success.