It stars Felix Avitia, Anndi McAfee, Aria Curzon, Jeff Bennett, Rob Paulsen, Frank Welker Nika Futterman, Meghan Strange, Tara Strong, Michael Kelley, Scott Menville, Hayden Rolence, Michael York, Issac Brown, Damon Wayans Jr. and Tony Amendola.
It is the first time James Horner's original themes (including instrumental uses of If We Hold on Together) from the first film are heard in a Land Before Time film since Journey to Big Water and the first time Meghan Strange voices Petrie's Mother. Like all the other Land Before Time movies, it is traditionally animated.
Littlefoot discovers a book that is about a legendary golden Longneck statue called the Golden Longneck (the Great Valley's main statue). When the book is stolen by the Great Valley's terrorist by the name of Emily, Littlefoot teams up with Cera, Petrie, Spike, Ducky, Chomper and Ruby to find the Golden Longneck and retrieve the book before Emily (whom Petrie's uncle, Pterano, works for) destroys it.
At the beginning, the Narrator introduces the Great Valley and tells the legend of it's statue called the Golden Longneck, which makes the Dinosaurs in the Great Valley happy. The legend happened before Littlefoot discovered the Great Valley. But years ago, the Golden Longneck disappeared. At the end of the prolouge, the narrator explains, "Now, it's up to Littlefoot the Longneck and his friends, Cera the Threehorn, Petrie the Flyer, Ducky the Swimmer, Spike the Spiketail, Chomper the Sharptooth, and Ruby the Fast-Runner to bring back the statue and bring back happiness."
In the present, Petrie just woke up and saw Spike dig for treasure with his tail. The treasure is a book about the Golden Longneck. Littlefoot, Cera, Ducky, Chomper the Sharptooth, and Ruby the Fast Runner arrive to see the book. The Golden Longneck vanished as a legend and went to the Cove of Wonders, an underground cavern in the outskirts of the Great Valley. Littlefoot suggests that he wil look for the Golden Longneck all by himself the next day. Littlefoot tells his grandpa that he is finding the Golden Longneck on his own in which he lets him go. Grandpa Longneck gave Littlefoot a map to read on his quest: He will go through the Hill of Fire (a volcano-like cave), go around the Rock of Fantasy (a sphere-shaped rock that cages dinosaurs every time they touch it), around the Destiny Flowers (flowers that make dinosaurs fall to a deep sleep every time they touch them), and to the Cove of Wonders to find the Golden Longneck.
That night, a terrorist of the Great Valley named Emily, the villain of the seventh film, Pterano, and her assistant, Smek, see the book and plot to tear the Book apart. Meanwhile, Littlefoot sneaks out of his home with the map. At sunrise, Cera, Ducky, Spike, Petrie, Chomper and Ruby walk up to Littlefoot, deciding to come with him. Grandpa Longneck, Grandma Longneck, Mr. Threehorn, and Guido look for Littlefoot and his friends. Ali, Shorty, Hyp, Mutt, Nod and Wild Arms decide to come along too.
Littlefoot and his friends went to the Rock of Fire. They walk through it, and while they are, Cera accidentally gets her tail burnt by the lava. Next, the friends went to the Rock of Fantasy and decide to go around it. Petrie accidentally touches it and gets locked in a cage. Spike carries the cage on his back. Next, the pals go to the Destiny Flowers. Ducky wonders what it does, touches a destiny flower and accidentally falls into a deep sleep. Littlefoot carries Ducky on her back.
Finally, Littlefoot and his friends go to the Cove of Wonders and the still-caged Petrie says, “Cove Ho!”. The pals go in and find the missing Golden Longneck. They meet up with Emily, Pterano, and Smek. The trio made it to the Cove of Wonders. Pterano is about to kill Littlefoot, but Cera blocks his way. She hits Pterano with her burnt tail. Pterano is burnt and loses his ability to fly. Littlefoot finds the Golden Longneck in the corner. Emily, Pterano, and Smek are about to kill Cera. Cera has a plan and defeats the villains by pushing her off the cliff. Littlefoot spots the Golden Longneck and uses it to free Ducky, Petrie, and Cera from their troubles. Littlefoot’s friends cheer. Grandpa Longneck, Grandma Longneck, Mr. Threehorn, Guido, Ali, Shorty, Hyp, Mutt, Nod and Wild Arms go into the Cove of Destiny and congratulate Littlefoot for finding the Golden Longneck.
With their mission to capture the Golden Longneck completed, Littlefoot, Cera, Ducky, Petrie, Spike, Chomper and Ruby are honored as heroes of the Great Valley by Littlefoot's grandfather. Littlefoot's friends and his grandparents start to go home.
In the post-credits scene, Pterano and Emily talk to each other about Littlefoot’s quest for the Golden Longneck statue. Pterano uses the Golden Longneck’s powers to make a rainbow.
- Owen Vaccaro as Littlefoot
- Anndi McAfee as Cera
- Aria Curzon as Ducky
- Rob Paulsen as Spike/Guido/Mutt
- Jeff Bennett as Petrie
- Frank Welker as Smek, a Carnotaurus and Emily's assistant
- Barry Bostwick as Grandpa Longneck
- Miriam Flynn as Grandma Longneck
- Michael York as Pterano, Petrie's uncle who seeks revenge on his nephew since his defeat in The Stone of Cold Fire.
- Nika Futterman as Emily, a Spinosaurus and the Great Valley's terrorist
- Tara Strong as Ali
- Michael Kelley as Hyp
- Scott Menville as Nod
- Damon Wayans Jr. as Wild Arms
- Scott Whyte as Bron
- Hayden Rolence as Shorty
- Jessica Gee as Tria
- George Ball as Mr. Threehorn
- Jackson Robert Scott as Chomper
- Meghan Strange as Ruby, Petrie's Mother and Ducky and Spike's Mother/Tricia
- Tony Amendola as the Narrator
- This is the first Land Before Time film that a character got a large stomach. First was Hyp, then Littlefoot, then Mutt, then Guido, and lastly, Ruby.
- This is the first film that Ali appears in but Old One does not.
- This is the second Land Before Time film to use more Hanna-Barbera sound effects, the first was Journey of the Brave.
- This is the first Land Before Time film to have a post-credits scene.
- This is the first Land Before Time film to have five songs instead of the usual three or four.
- This is the sixth film in which Littlefoot and Ducky are shown crying. They cry three times.
- This is the first film in which Ruby cries. She cries four times.
- With the running time of 106 minutes, this is considered the longest Land Before Time film.
- It is also currently Universal's third longest animated direct-to-video production.
- Wild Arms, Hyp, Mutt, Nod, Guido, Ali, and Shorty appear as secondary characters. They search for Littlefoot and his friends, who are finding the Golden Longneck along with Bron, Grandpa Longneck, and Mr. Threehorn.