3. Selling off a large amount of land

The biggest obsticle standing in the way of Universal's master plan to beat Disney in Orlando is size. Disney has an absolutely enormous plot of land on which they could build any number of new theme parks. Universal doesn't have that luxury.

But that wasn't always the case.

In 1998, Universal bought 2,000 acres of land from Lockheed Martin nearby the original Universal Orlando property. The plan was to turn that land into two more theme parks and several new resort hotels – expansion that would ultimately put Universal on par with Disney in terms of its entertainment offerings. Its prime location across from the Orange County Convention Center was another selling point, presumably attracting conventioneers to check out the new resort.

However, in 2003, Universal was forced to sell off 1,800 acres of that land due to the company's financial difficulties.

Oops.

Nowadays, Universal is one of the most exciting and profitable entities in Central Florida, and it's now bursting at the seams with creativity. They're currently building a new hotel, a new attraction, and possibly even a new water park – all without using that 1,800 acres they unfortunately had to sell off.

Could you imagine what the current Universal management could do with that amount of space? With the ambition they've shown in recent years, dumping all of that land has proven to be one of the most costly mistakes in Universal's history. 

4. The Grand Saga of Marvel Comics

The story of the theme park rights for Marvel Comics is long and complex enough to have a novel written about it. In fact, the story is so twisting and turning that we aren't even finished writing it yet, and the ending has never been murkier to predict.

Let's take a step back: In the planning stages for Universal's Islands of Adventure, the company secured the theme park rights to all of Marvel's characters. It's because of this deal that we've been treated to the Amazing Adventures of Spider-Man all these years. However, in 2007, Universal opted not to renew its agreement in its entirety and forfeited the rights for the western half of the United States – continuing to hold the deed east of the Mississippi River.

But then, in 2009, Disney bought Marvel. And now things are totally insane.

Although it owns the company, Disney cannot build any attractions using any Marvel characters anywhere east of the Mississippi – including Walt Disney World. And despite having one of the most popular and successful Marvel attractions on the plane, The Amazing Adventures of Spider-Man, Universal cannot build anything using those characters west of the Mississippi – meaning they could not build a version of that attraction at Universal Studios Hollywood.

Here's the upshot: Disney's going to keep making movies using the Marvel characters because those movies have made the company an insane amount of money. However, if they ever want to leverage those characters with a presence in their theme parks, they have to purchase those rights back from Universal. Had Universal held onto the West Coast rights, that purchase price would be astronomically high – perhaps even high enough for Universal to buy some of that land back. And then, well, it's off to the races for both parks.

Instead, Universal gave away those rights for nothing, and now Disney can build Marvel attractions out in California and use the uniqueness as a selling point to draw East Coast fans to the West – thereby removing the pressure on Disney to get a deal done.

Still, this particular blunder is ongoing and hasn't yet been resolved. There's a chance Universal uses the Marvel rights to make a big play that positions the company perfectly for the future, in which case, we'll probably have to redo this list.