The Walt Disney Company rightfully gets all the credit for its seamless implementation of Disney theme parks around the world. Generally, every new park, themed land, and attraction opens almost perfectly. Sure, a glitch happens here and there, but extensive internal quality assurance has helped the company avoid most major snafus. It’s how a complex themed land like Pandora – The World of Avatar or a revolutionary park like Shanghai Disneyland garners such instant and total acclaim. Still, some occasional snafus are inevitable. Here are five Disney attractions that had almost immediate problems.

Expedition Everest

Image: DisneyMath errors. We all make them. Sure, everyone remembers a moment of pride here or there when they scored 100 on the big math test, but incorrect calculations are a part of life. Maybe you’ll expect your groceries to cost less or you’ll spend more on your theme park vacation than you projected. A misplaced comma here or there is enough to mess up any mathematical computation.

Imagine if you worked at a Disney theme park and messed up your math! Think about the potential ramifications that would cascade from this single mistake. Sadly, some (group of?) Imagineer(s) somewhere lives with this frustration every day. They made a miscalculation that will live on in theme park infamy for years to come.

Back in the planning phase of Expedition Everest, Disney knew that the Yeti would highlight the attraction. They also understood that it would be one of the largest audio-animatronics ever. To secure it in the attraction, Imagineers built it into the base of the structure…but there was a problem. They incorrectly calculated the amount of weight that the base could support. The pressure from the Yeti exceeded that weight.

Yes, the Yeti’s movements risked fracturing the foundation of the adjoining mountain. And it was all because of a math error. Today, the creature nicknamed the Disco Yeti only performs a fraction of his possible movements lest he collapse the mountain at his feet.