In Coco, Ernesto de la Cruz might be handsome and charming, but there are clear indicators that the Spanish crooner is far more devious and dangerous than he appears. A big clue is "his" guitar.  

If you take a good look at the guitar that is closely associated with Ernesto – the one that hangs in his shrine – the headstock has a skull head with a gold tooth. If one was to examine Ernesto's own pearly whites, they might notice that there isn't a single gold tooth among them.  

But you know who does have a gold tooth? Hector.  

The guitar is clearly Hector's, who made to resemble himself, not his singing partner Ernesto. When Ernesto poisoned Hector, he stole his music and his guitar. The gold tooth of the guitar was a small hint that something was amiss with the beloved singer.  

(Small note: Hector probably painted it while looking at a mirror, which is why it's on the wrong side.)

The Incredibles holds a lot of dark, hidden details when diving into the nitty gritty of the story. And no wonder, considering the main villain is serial killer of supers.  

According to a bonus feature on the DVD title "NSA Files," a superhero group titled The Phantasmics originally used the island as their headquarters. Led by Everseer, the team consisted of Macroburst, Plasmabolt, and Psycwave and focused on alleviating international threats. At one point Gazerbeam was part of the crew as well, but had a falling out with Everseer.  

All members of the team, including defunct member Gazerbeam, were murdered on the island by Syndrome and his Omnidroid before he took it over. That is how he got the island.  

(It should be noted that Macroburst was the only super to defeat Omnidroid v.X1 during the training sessions for Operation Kronos, but was eventually killed by its successor.)

...because he is a killer of careers and dreams.

Before becoming Ratatouille's biggest supporter, food critic Anton Ego was known as a destroyer of careers for chefs all around Paris, as his reviews have brought down restaurants throughout the land.

To expound that fact, his tool of the trade and the place where he practices his craft illustrate his precision as a dream killer, as his office and his typewriter resemble a coffin and a skeleton head, making the critic seem so much more sinister.

"No, can't go. I can't do storage again, I just can't! I won't go back in the dark!"  

When Jessie is confronted with the possibility of returning to the dark abyss of storage, Stinky Pete the Prospector calms her down, attempting to sooth the panicked cowgirl. What the audience might not realize is that Jessie's fear comes from a place of deep trauma, having been in solitary confinement for years after she was abandoned by her owner Emily.  

After Jessie the Yodeling Cowgirl is discarded to a charity by Emily in the early '70s, she spends an undetermined amount of years before she is found by Al where he places her in storage. Alone in the dark, Jessie is left with only her thoughts to keep her company, slowly going mad by her situation. Her only hope is the discovery of Sheriff Woody Pride to save her, to complete the collection so it can be sold to a museum in Japan.  

But soon, that seems like a far off dream.   One can only imagine her disappointment when Al finds Woody only for him to not want to join Jessie at the museum in Japan as part of a collection. Her fear is tangible and honestly, completely understood.

When Bob is chatting with Edna about his new costume, the fashion designer is adamant about her stance on the iconic superhero accessory. Absolutely, positively, no capes. She then lists all the deaths of heroes caused by capes. Thunderhead was snagged on a missile fin while teen hero Stratogale was sucked into a jet turbine while flying next to an aircraft. Meanwhile, Metroman was pulled down by an express elevator, Dynaguy was snagged on takeoff, and Splashdown, sucked into a vortex.  

Five. Five deaths. All caused by costume-related failures.  

These deaths probably weighed heavily on the head of Edna Mode over the years, who looked to the heroes as gods. One can only imagine the inner turmoil that occurred after the demise of each hero.  

Does anyone really blame Edna when she tells Bob "NO CAPES!" with such fervor?

Much like HAL 9000 from 2001, Auto the Autopilot for the Axiom in Wall-E is driven by his main directive to commit atrocities against the passengers of the ship. Yes, he was programmed to carry out Shelby Forthright’s Directive A-113, but like HAL, he also has self preservation in mind.  

Thanks to a small detail early in the film, it was clear that the ship's artificial intelligence had its own agenda.  

In portraits of past Axiom captains there are hints about the ship, its crew, and its history that are revealed. In addition to the captain growing significantly larger due to the lack of exercise available on the ship, their lifespans are also lengthened by decades. But a key piece of foreshadowing in the portraits is Auto in the background.  

With each portrait, Auto inches closer and closer, creeping on the captain as if to gain more control of the ship and its captain. Which is exactly what the AI was doing for years and years. Until finally, Auto almost shares the portrait completely with current leader, Captain B. McCrea.  

It is a creepy realization that Auto has slowly been taking over in the last century without anyone's knowledge, but the images are evidence to its evil agenda.

A small, seemingly insignificant detail in Coco that fans noticed adds a sinister layer to the Land of the Dead that deals with one of the background skeletons.  

After Miguel crosses the marigold bridge, some audience members notice a resident of the underworld who looks a lot like drug lord Pablo Escobar among the undead up. And it appears he is up to his old tricks as he accepts a small baggie of an unknown substance from another skeleton. Fans have speculated that it is the notorious criminal continuing his trade in the Land of the Dead.

In Ratatouille, when Remy's vermin brethren are raiding Gusteau's pantry, there is a quick flash to a canister of expensive caviar sitting on the shelf. If one was to pause and look closely, it is Nemo brand.  

Perhaps that barracuda didn't eat all of Nemo's brothers and sisters. Maybe they were appetizers.

Best known for making grown men cry like a little girl within the first 20 minutes of viewing, Up is a masterclass in emotional gut punches. But in addition to its heart wrenching story are the small details the film uses to highlight the emotional turmoil of its characters.

A perfect example of this is in the character of Ellie and how she is remembered by her husband after she passes away.  

In the beginning of the film as audiences get to know Ellie, she is represented by vibrant colors to illustrate her vibrant personality. After she passes, the film and its colors become muted, as Carl Fredricksen's life has become wearisome without his wife. But around the house, only Ellie's items retain their color. Her parrot statue, the grape soda pin she gave Carl, her side of the bed... items of great importance in her life hold the only color in Carl's life, just as his wife was the only tint of joy. 

At that point, of course. Happiness was right around the corner for Mr. Fredricksen.

Granted, Toy Story of Terror is a Halloween tale meant to thrill the little ones, but even for the spooky seasonal scare, this is a little dark.  

Deceased hero Gazerbeam, whose exploits and demise are only discussed in the first Toy Story film (and a few DVD extras), gets a creepy little shout out in the Halloween special. Gazerbeam, who was killed in The Incredibles by Syndrome and the Omnidroid, has a tombstone that uses his citizen name of Simon A. Paladino, a reference that can only be caught if one was to pause on the "Man Missing" newspaper clip from The Incredibles.  

The tombstone reads, "A public servant with a unique vision."

"Four is the worse number."  

This is a sentiment that is echoed a few times by Grandma Wu in Pixar's 25th full feature film,  Turning Red. And with good reason. In Chinese culture, the number four is considered unlucky by many because in Cantonese, it is pronounced similarly to the word for "death" (死, pinyin: sǐ).  

As a result, some Chinese buildings often don't have a fourth floor.  

In contrast, the number eight is very lucky, as it sounds like "fa," which translates to "fortune."

When audiences first meet young Sid, he appears as a slightly demented young man with a penchant for destruction as he gleefully destroys toys. By the end of Toy Story, the sentient toys come to life and take their revenge, possibly destroying the young boy's psyche in the process as he realizes that all the toys he tortured were alive the entire time.

The next time audiences appear to see Sid, it is many years later in a small cameo in Toy Story 3. Seemingly happy and well adjusted now, Sid appears to be a sanitation worker, still bearing the same distinct skull t-shirt he did as a child.  

Then in Coco, eagle-eyed fans noticed a dark detail in the form of a skeleton wearing Sid’s skull shirt. Many have speculated that the undead citizen of the Land of the Dead is the one-time destroyer of toys who has now passed on.  

(Please note, because of the skeleton's haircut and keyboard setup, others have surmised that this is the underworld's version of Skrillex, which depending on a person's taste in music, can also be a dark detail.)

When Helen Parr returns to her role as Elastigirl in The Incredibles 2, she initially suffers from pangs of guilt for leaving her family for the job. But after saving a train and a few hundred lives, she's elated with her return to crime fighting and can't wait to call husband Bob to share it with him.  

As she talks to a despondent and exhausted Bob about her exciting day, the conflicting tone of the two moods set the scene. While Helen is delighted, Bob misses his wife, but doesn't want to derail her happiness.  

In Helen's hotel room, hiding in plain sight, is a painting that represents Bob's feelings on the matter. A representational art seems harmless, but portrays each member of the Parr family, with Helen far off to the side, apart from the rest. The hotel room painting is a clever way for the filmmakers to convey Bob's feelings of abandonment from Helen and dejection for not being chosen as the hero.