It was released to cinemas 24 years ago - but some Disney fans have only just clocked a major Easter egg in Monsters Inc. The 2001 animated movie follows best friends Sulley and Mike trying to work their way up the ranks at Monsters Incorporated, an energy company which requires monsters to scare children.

However, their lives are hugely disrupted when a human girl wanders into the monster world - simultaneously scaring them while stealing their hearts. In the movie, Sulley names the two-year-old Boo while she nicknames the big blue monster Kitty.

However, some fans have only just realised Boo's real name is hidden in a split-second clip within the movie - and the writers put a great deal of thought into it too.

In the scene where Boo is sat in bed showing off her drawings to the monsters, you can see her human name written on the top of a piece of paper - Mary.

Commenting on this revelation, one user said: "When I was little this movie made me realise that you should always sign your work when you draw and I still do it."

Another user added: "We definitely weren't able to read it on the tube TV when this movie came out."

It turns out Boo was named after her voice actor Mary Gibbs, who was a toddler at the time of recording.

The now 28-year-old's voice was also used in The Lion King II: Simba's Price and Baby Kiara, Monsters University as Girl in cabin, Inside Out as Baby Riley, and The Last Guest as Charlotte.

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Mary suffered from scoliosis as a teenager before undergoing surgery in 2012 and returning to acting in 2022, voicing Janessa Jensen in Heroes of Extinction.

She has also answered fan questions on Reddit and YouTube about her time as Boo in the Disney Pixar movie.

When asked how many times she has watched the movie and whether it feels "weird" to hear her toddler self, she said: "Especially when the movie first came out everyone wanted to watch it with me. I've probably seen it a couple hundred times.

"Now that I'm older its a little weird knowing that's my voice for sure! It really hit me when I rode the Monsters Inc ride at California Adventures and my voice was all over the ride.

"Then again it doesn't really seem like me when I watch it. It's hard to explain the mixed emotions I get when watching the film now."

Another user asked: "How did they get you to record the part in Monsters Inc? Sit you down in a booth, or follow you about with a microphone whilst you did 'kid' things?

In response, she said: "They would follow me around the recording studio, use puppets to talk to me, and have my mum tickle me or take money/candy away from me to make me laugh and cry ahaha all real emotions."