Littlefoot and The Adventures of the Great Mouse Detective is another Land Before Time crossover film planned to be re-edited by Yru17. It is unknown when the film will be shown on YouTube.
Littlefoot, his grandparents, and his friends (along with Ash, Stan, Mickey, Johnny, Gumball, their friends and their families) take a time-traveling vacation to London in 1807 and meet Basil of Baker Street, Dr. David Q. Dawson, and Olivia Flaversham as they solve thier mystery, find Olivia's father Hiram Flaversham, and battle against Ash's old enemy Professor Ratigan, whom Carface, Killer, Oogie Boogie, The Grand Duke of Owls, Makunga, Pete, Lord Rothbart, Dr. Facilier, Ursula, and Team Rocket (Jessie, James, and Meowth) work for.
- Ash Ketchum, Pikachu, Misty, Brock, Togepi, Stan Marsh, Kyle Broflovski, Eric Cartman, Kenny McCormick, Mickey Mouse, Pluto, The Vultures (Buzzie, Flaps, Dizzy, and Ziggy), Jiminy Cricket, Zazu, King Julien, Maurice, Mort, Terk, Tantor, Princess Tiana, Prince Naveen, Louis, Ray the Firefly, Genie, Jesse Greenwood, Elvis, Randolph Johnson, Nadine, Jean-Bob, Speed, Puffin, The Goonies (Mikey Walsh, Brand Walsh, Mouth Devereaux, Data Wang, Chunk Cohen, Andy Carmichael, Stef Steinbrenner, and Sloth Fratelli), Sebastian, King Louie, Fu Dog, Kenai, Koda, Rutt and Tuke, Roger Rabbit, Chanticleer, Jack Skellington, Scooby-Doo, Shaggy Rogers, Fred Jones, Daphne Blake, Velma Dinkley, Rex, Woog, Elsa, Dweeb, Charlie Barkin, Itchy Itchiford, Johnny Test, Dukey, Susan Test, Mary Test, Hugh Test, Lila Test, Gumball Watterson, Darwin Watterson, Richard Watterson, Nicole Watterson, Anais Watterson, Carface, Killer, Oogie Boogie, The Grand Duke of Owls, Makunga, Pete, Lord Rothbart, Dr. Facilier, Ursula, and Team Rocket (Jessie, James, and Meowth) guest star in this film.
- The main reason Scooby-Doo and the gang are in this film is because they are mystery solvers just like Basil of Baker Street.
- The Vultures and Zazu make their full guest appearances in this film, despite their minor appearances in SpongeBob and Friends Meet The Great Mouse Detective.
- Ash and the gang met Ratigan and Fidget before in Winnie the Pooh Meets Snow White and the Seven Dwarfs, but the reason they're in this film is not only so they would meet Basil of Baker Street, but also because they were requested to be in it.
- Aladar, Neera, Pilo, Yar, Suri, Zini, Baylene, Eema, and Url were originally going to guest star in this film, but the idea was dropped because Yru17 decided to re-edit this film before Littlefoot and The Return of Jafar and Littlefoot's Adventures of Dinosaur since Pooh's Adventures of Total Drama Island will not only guest star Littlefoot and his friends, but will also guest star Ratigan and Fidget with Jafar, Iago, and Maleficent, so Yru17 decided to re-edit Aladar and The Adventures of the Great Mouse Detective instead.
- Like DisneyAnimeManiac's film Winnie the Pooh in The Adventures of the Great Mouse Detective, this is an NTSC film with NTSC bits from The Land Before Time films, the Pokémon films, South Park: Bigger, Longer & Uncut, Mickey, Donald, Goofy: The Three Musketeers, the Mickey Mouse films, the The Princess and the Frog, the Aladdin films, The Jungle Book 1 and 2, Pinocchio, The Lion King films, Free Willy 1-3, the Madagascar films, The Swan Princess films, the Tarzan films, The Goonies, The Nightmare Before Christmas, the Scooby-Doo films, We're Back! A Dinosaur's Story, and the All Dogs Go to Heaven films and more.
- Like in Winnie the Pooh in The Adventures of the Great Mouse Detective (in which Winnie the Pooh was kidnapped with Olivia by Fidget), Littlefoot, Ducky, Petrie, Chomper, Guido, Pikachu, Togepi, Kyle, Cartman, Mickey, Pluto, The Vultures, Jiminy Cricket, Zazu, King Julien, Maurice, Mort, Tiana, Naveen, Louis, Ray, Genie, Jesse, Randolph, Jean-Bob, Speed, Puffin, Mikey, Mouth, Data, Chunk, Sebastian, King Louie, Rutt, Tuke, Roger, Chanticleer, Jack, Scooby-Doo, Shaggy, Elsa, Dweeb, Charlie, Itchy, Johnny, Dukey, Gumball and Darwin will be kidnapped with Olivia by Fidget while Cera, Spike, Ruby, Grandpa Longneck, Grandma Longneck, Ash, Misty, Brock, Stan, Kenny, Terk, Tantor, Elvis, Nadine, Elvis, Nadine, Brand, Andy, Stef, Sloth, Fu Dog, Kenai, Koda, Fred, Daphne, Velma, Rex, Woog, Susan, Mary, Hugh, Lila, Richard, Nicole and Anais will team up with Basil and Dawson.
- Littlefoot and his friends will face Ratigan and Fidget again in Pooh's Adventures of Total Drama Island.