We all have happy memories of visiting Disneyland - the "happiest place on earth" - as kids. But when you revisit the park as an adult you pick up on things that you might have missed before.

It turns out the park has a long and surprisingly dark history. Here are 10 examples you won't read about in any guidebooks:

1. The park plays with your head

From the moment you step onto Main Street USA, the park is using a lot of sneaky tricks to play with your mind. Different scents are piped into parks of the park - fresh baked cooks, apple pie, horse manure - to influence your emotions and guide you around the park.

One of the park's signature tricks is the ride time signs. If you crunch the numbers, these helpful warnings actually advertise the time in line as 1/3 longer so you feel grateful and happily surprised by the time you get to the front. Even the clocks tick more slowly to keep up the illusion.

2. The Fantasmic duck roast

It turns out Donald Duck is lucky to be around, because Disneyland lost a lot of good ducks in a fiery accident. Disney historian and author David Koenig revealed that Disney engineers had to retool the "Fantasmic!" sound and light show to protect the park's feathered residents.

The show's finale involves the dragon from Cinderella setting the Rivers of America on fire. "What they quickly discovered when they first had the show was that the ducks that liked to hang out on the river were being cooked," Koenig said. Today, the rivers "bubble" before the fire-breathing scene to scare ducks away.

3. There have been a surprising number of deaths in the park

By the official count, 9 people have lost their lives inside the park, usually because they didn't follow directions on rides. A surprising number of the deaths involved guests trying to jump between the People Movers, and another person was hit in the head by the Sailing Ship Columbia when a rope holding it in place broke.

Disney World has had its share of tragedies as well. A little boy was famously eaten by an alligator at Disney's Grand Floridian resort in 2016. Another guest died in 1980 after catching a brain-eating parasite from the waters of Disney World's River Country attraction, which originally used un-chlorinated water.

4. The Haunted Mansion is really haunted

While no guests have met their doom while riding in a Doom Buggy, it's safe to say the popular attraction has its fair share of spirits. That's because the grisly ride has become a popular final resting place for serious Disney fans. There have been a number of reports of guests pouring out their loved one's ashes while on the ride.

The morbid tradition is so common that the ride's staff will actually warn you not to pour out any remains as you board. In case you were curious, it's illegal to dump ashes on private property, including theme parks.

A handful of attractions at the park have been removed for being too adult...

5. The Wizard of Bras

One of the park's original attractions was a store called the "Hollywood-Maxwell Brassiere Co. Of Los Angeles." It featured an exhibit on the history of underwear, and a souvenir store which sold bras and corsets. In another section, a character named the Wizard of Bras posed among female mannequins in their underpants.

Needless to say the store was a questionable attraction at the family-friendly park. It closed just 6 months later. Strangely, another lingerie store opened in Disneyland in 1990 to promote Who Framed Roger Rabbit? The boutique, called Jessica's, sold lingerie, bras and Jessica Rabbit merchandise.

Disneyland also had a tobacco and cigar shop until 1991. You can spot its old location by looking for the wooden Indian statue on Main Street USA.

6. Not all of the Pirates of the Caribbean are animatronics

One of the quirkiest facts about the park's signature attraction is that when it was built in 1967 the designers refused to use fake-looking skeleton props as decoration. Instead, they used real skeletons from UCLA's medical center.

Disney producer Jason Surrell insists that the skeletons were "later returned to their countries of origin and given a proper burial" once suitably fake-looking skeletons were found. But a few park staff members insist there are still real skeletons and skulls haunting the ride.

7. Black Sunday

What was meant to be Disneyland's moment in the sun turned out to be a total disaster that is still remembered decades later. After spending decades planning the park and pouring $17 million of his own money into the project, Walt Disney finally opened his creation in 1955.

But from start to finish the day was a mess. The park was full of guests as 13,000 people used fake tickets to get in, meaning vendors ran out of food and drinks very quickly. It was so hot that women's high heels were sinking into the pavement, but the water fountains were not working.

To top things off, the park's biggest attractions (including the Dumbo ride and Rocket to the Moon) were still under construction. All in all, not a great start to the park's history.

8. The hippy invasion

Another little-known event from the park's history involved more than 200 anti-war protesters called the Yippies (for the Youth International Party) who descended on the park in 1970. The college students used their invasion of the park to protest the Vietnam War, and they briefly occupied Tom Sawyer Island before being driven out of Disneyland by riot police.

9. The Disneyland cats

You would think that Disneyland is the one place mice are welcome, but it's not so. To keep the rodent population under control, Disney relies on more than 200 feral cats who live on the park's grounds and emerge at night to hunt for vermin.

The cats have a long history in the park, moving into Cinderella's Castle shortly after it opened in the '50s. Since then they've become a tolerated but not exactly welcome feature. The park has even built special "cat houses" for them to relax in.

10. Watch out for "Code V"

Like other jobs, being a Disneyland "cast member" comes with its own secret code that lets employees talk about guests within earshot. One of the most famous examples is a "Code V," which you might hear being announced at some of the more exciting rides.

Of course the V stands for "vomit," and it means that someone has made a mess of one of the rides (which happens way more than you would expect). Also listen close for "Have a Disney day!" which is an official Disney greeting but also a polite way to say "Get lost!" to annoying guests.

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