After a cloud of swarming locusts descends upon Great Valley, devouring all plants and leaving it a barren wasteland, the inhabitants must seek another place where they can survive until the plants in Great Valley have grown back. However, the Leaf Gobblers have left a path of devastation behind them, leaving no food for the dinosaurs to find. After erring for days and days through this desolation, the herd quarrel and threaten to separate. The main characters do not want to be separated, so they set out to find a location with plentiful food. They leave a trail for the grownups to find them with, and eventually reach the "Big Water" (ocean). There, they see a verdant island connected to the mainland by a thin land bridge. On their way, an Tsunami occurs, which they narrowly escape, and which wipes out the bridge.
Isolated on the island, they try out Cera's idea to return by using a log as a boat (which made her seasick). However, a Megalodon ("swimming sharptooth") attacks, and in the confusion and fright which follows, they end up on the island again. That night, they remember their families, while the herd, who followed the trail, sleep on the shores of the beach on the mainland, worrying for them.
The next morning, the children and Pooh and the others wake up to the shadow of a Sharptooth. They take off, but find themselves cornered by high cliffs. They huddle together when the sharptooth approaches, only to find that it is Chomper (from Kids World's Adventures of The Land Before Time II: The Great Valley Adventure). He then helps them to hide from his parents(he can talk now unlike before when he was a baby) , who are also on the island, and provides them with food upon their request. However, an overcautious Cera openly displays distrust to Chomper because he was a Sharptooth, which grieves him, and he departs. Littlefoot follows him and apologizes, but is interrupted by Chomper's mother. She nuzzles him, then leaves, presuming Littlefoot is prey. Littlefoot is intrigued by her display of love to Chomper.
Meanwhile, another Sharptooth Giganotosaurus living on the island finds the children and our heroes, and gives them chase. Chomper tries to help, but the Sharptooth overcomes him. His parents then come and battle the Sharptooth near the edge of the island, during which he falls into the Big Water and takes Chomper with him. Littlefoot plunges in to save Chomper while the sharptooth is swept away by the current. Another "swimming sharptooth" appears, but they discover it was an Elasmosaurus named Elsie who then saves the two from drowning. She returns them to the island, where Chomper's grateful family promises never to harm the children and Pooh and the others. Still, the gang miss their families, so Elsie offers to take them across the sea, making Cera even more seasick than before. They say their final goodbyes to Chomper, and board Elsie. When back on the mainland, they find out that the herd found a lush, green, little place on the shore to stay in till the Great Valley is green again.
- The Fraggle Rock Gang, Roary the Racing Car, SpongeBob SquarePants, Patrick Star, Bloom, Stella, Flora, Musa, Tecna, Layla, Roxy, Simba, Timon, Pumbaa, Zazu, Terk, Tantor, Baloo, Bagheera, King Louie, the Vultures (Buzzie, Flaps, Ziggy, and Dizzy), Jiminy Cricket, Alex, Marty, Melman, Gloria, the Penguins of Madagascar (Skipper, Kolwalski, Rico, and Private), Genie, Louis, Roger Rabbit, Danny, Sawyer, Rex, Dweeb, Woog, Esla, Rapunzel, Pascal, Flynn Rider, Maximus, Jean-Bob, Speed, Puffin, Chanticleer, Wilbur the Albatross, Owen, Lindsay, Beth, Strawberry Shortcake and her friends, Danny Phantom, Sam Manson, Tucker Foley, Jazz Fenton, Danny, Sawyer, Jean-Bob, Speed, Puffin, Rex, Dweeb, Woog, Elsa, Rapunzel, Pascal, Flynn Rider, Maximus, Chanticleer, Wilbur the Albatross, Bob the Tomato, Larry the Cucumber, Junior Asparagus, Hercules, Megara, Philoctetes, Pegasus, Alice, Pocahontas, Meeko, Flit, Princess Aurora, Prince Phillip, Peter Pan, Tinkerbell, Rosetta, Silvermist, Idressa, Fawn, Oliver, Dodger, Lucky, Cadpig, Rolly, Spot the Chicken, Woody, Buzz Lightyear, Jessie, Tommy Pickles, Chuckie Finster, Simon, Theodore, Brittany, Huckle, Lowly, Woody Woodpecker, Ord, Cassie, Arthur Read Bobby, Cindy, Oliver, Millicent, Greg, Marcia, Peter, Jan, Matthew, Dwayne, Steve, DJ, Stephanie, Michelle, Alex and Nicky, Teddy, Aaron, Denise, Derek, Harry, Rusty, Walter, Casper, Wendy, Kevin McCallister, CeCe, Rocky, Davis, Kelly, Lynn, Pebbles, Bamm-Bamm, Davey, Goliath, Tommy, Dil, Chuckie, Phil, Lil, Kimi, Angelica, Susie, Savannah, Nichole, Z, Doggie Howser, Cake, Miracle, Amy, Benjamin, Alex, Leah, Buffy, Jodi, Little Carbon Soldiers, Vada, Ryan, Noak, Thomas J., Mary Ann, Kaia, Jane, Gina, Teddy Bear, Jack B. Nibble, Little Bo Peep, Baa, Baa Sheep, Mary Quite Contrary, Eep Mouse, Gobo, Red, Mokey, Wembly, Boober, The Doozers, Pablo, Tyron, Tasha, Uniqua, Austin, Flynn, Gunther, Tinka, Leo Little, Carly, Sam, Freddie, Spencer, Kimmy Gibbler, Shirley Temple, Gibby, Daniel Cook, Emily Yeung, Gabriella, Gerald, May, Sid, Alvin, Simon, Theodore, Brittany, Jeanette, Elanor, Millie, Geo, Bot, Caillou, Leo, Sarah, Rosie, Clemintine, Julie, Andre, Jason, Jeffory, Jonus, Emma, Xavier, Billy, Gilbert, The All That Gang, Hannah Montana, Miley Stewart, Lilly, Lola, Oliver Oken, Mike Standley III, Jackson, Robby, Rico Suave, Malcolm, Mallory, Resse, Renee, Dewey, Daisy, Chyna Parks, Olive Doyle, Fletcher Quimby, Lexi Reed, Cameron Parks, Becky O'Shea, Junior Floyd, Jake Berman, Rudy Zolteck, Tad Simpson, Hanon, Murphy, Marcus, Timmy Moore, Nubie, Johnny Vennaro, Briggs, Patterson, Priscilla O'Shea, Debbis O'Shea, Calvin Cambridge, Murph, Ox, Marlon, Reg Stevens, Spanky, Stymie, Froggy, Porky, Buckwheat, Uh-Huh, Waldo, Mary-Anne, Jane Twin #1 & 2, Darla, Alfalfa, Tessie, Sharkboy, Lavagirl, Max, Linus, Marrisa, Nigel, Kyle, Mike, Mark, Jessica, Kimberly, Sarah, Jake, Henry, Lorraine, Cooper, Dylan Schenk, Quinn, Aldo, Ethan, Marrisa, Bina, Ely, Otter, Lau, Mick, Christina Beardsley, Harry Beardsley, Michael Beardsley, Kelly Beardsley, Phoebe, Naoko North, Joni North, Jimi North, Paisley Houndstooth, Darryl Parks, Roxanne Parks, Becky Murtaugh, Kenneth Murtaugh, Elliott Murtaugh, Daniel Murtaugh, Lisa Murtaugh, Robin Murtaugh, Bindi, Rosie, Matilda, Lavender, Bruce, Arena, Ben Hilton, Jamie, Max, Becca, Nicky, Jeannie, The Flash/Tony, Crispin, Dylan, Duncan, Sean, Tony's Brother, Juel, Erin, Twist, Kiki, Marina, Shout, Dragon, Alligator, Ostrich, Beaver, Cat, Mailmouse, Dennis Mitchell, Joey, Gina, Margaret, Gunther, Hector, Jessica, Lisa, Keith Watson, Marcus Barnes, Susan Evers, Sharon McKendrick, Sharon Ferris, Susan Carey, Hallie Parker, Annie James, Kady Jay Kyle, Franklin Aloyisious Mumford & Friends, Peter Pan, Wendy Darling, John Darling, Michael Darling, Slightly, Nibs, Curly, Twin #1 & 2, Tiger Lily, Tootles, Messenger Boy, Young Wendy, Young Skeeter, Madeline, Aggie, Victoria, Chantel, Lucinda, Serena, Sylvette, Veronica, Lolo, Julie, Beatrice, Taylor, Jackson C., Madeline Riggs, Morgan Riggs, Derek Venturi, Casey MacDonald, Richelle, Reese Ambler, Rydell, Becky, Kimberly, Dylan and their friends, Lizzie MacDonald, Edwin Venturi, Marti Venturi, Vicki, Truman French, Tina Kathleen Miller, Ramona, Beezus, Cory Baxter, Newton Livingston III, Meena Paroom, Sophia Martinez, Haley, Nat Wolff, Alex Wolff, Thomas, David, Qaasim, Cooper Pillot, Jesse Draper, Tanner Boyle, Ahmad Abdul Rahim, Amanda Wurlitzer, Engelberg, Jose Agilar, Regi Tower, Miguel Agilar, Kelly Leak, Ogilvie, John, Peter, Quinn, Jimmy Feldman, Rudi Stein, Tony Thompson, Rudolph Sackville-Bagg, Anna Sackville-Bagg, Gregory Sackville-Bagg, Timmy Lupus, Eric, Charlie, Nicole, Dena, Jared, Riley, Stacy, Kenny, Lauren, Anthony, Robin, Ana, Haylie, Ryan, Connie, Gloria, Flip, Devyn, Mickey, Richie, Annie, Jamal Jenkins, Lenni Frazier, Alex Fernández, Gaby Fernández, Tina Nguyen, Rob Baker, Héctor Carrero, Casey Austin, CeCe Jenkins, Greg, DJ, Malcolm, Daniel Cook, Stan Marsh, Kyle Broflovski, Eric Cartman, Kenny McCormick, Alex, Marty, Melman, Gloria, King Julien, Maurice, Mort, Terk, Tantor, Taran, Princess Eilonwy, Fflewddur Fflam, Gurgi, Orddu, Orgoch, and Orwen, Aladdin, Princess Jasmine, Abu, Genie, Iago, Brer Rabbit, Jesse Greenwood, Elvis, Randolph Johnson, Nadine, Fievel Mousekewitz, Tiger, Tony Toponi, Tanya Mousekewitz, Yasha Mousekewitz, Papa Mousekewitz, Mama Mouskewitz, Ariel, Flounder, Sebastian, The Goonies (Mikey Walsh, Brand Walsh, Mouth Devereaux, Data Wang, Chunk Cohen, Andy Carmichael, Stef Steinbrenner, and Sloth Fratelli), Baloo, Bagheera, King Louie, Manny, Sid, Diego, Charlie Barkin, Itchy Itchiford, Sasha, Fu Dog, Kenai, Koda, Rutt and Tuke, Roger Rabbit, Mickey Mouse, Donald Duck, Goofy, Scrooge McDuck, Huey, Dewey and Louie, Webby, Bugs Bunny, Daffy Duck, Resse, Ryndall, Robin Hood, Little John, Wilbur the Albatross, Mrs. Brisby, Jeremy the Crow, Jean-Bob, Speed, Puffin, Ttark, Woody Woodpecker, Slimer, Stay Puft, Toaster, Lampy, Radio, Blanky, Kirby, Jimmy Neutron, Carl Wheezer, Sheen, Cindy Vortex, Libby, The Muppets (Kermit the Frog, Fozzie Bear, The Great Gonzo, Miss Piggy, Rowlf the Dog, Scooter, The Eletric Mayhem, Rizzo the Rat, and Walter), Fred Flintstone, Wilma Flintstone, Pebbles Flintstone, Dino, Barney Rubble, Betty Rubble, Bamm-Bamm Rubble, George Jetson, Jane Jetson, Judy Jetson, Elroy Jetson, Astro, Rosie the Robot, Mr. Spacely, Yogi Bear, Boo-Boo Bear, Snagglepuss, Huckleberry Hound, Quick Draw McGraw, Augie Doggie and Doggie Daddy, Wally Gator, Magilla Gorilla, Top Cat, Peter Potamus, Scooby-Doo, Shaggy Rogers, Fred Jones, Daphne Blake, Velma Dinkley, Scrappy-Doo, Rex, Woog, Elsa, Dweeb, Jack Skellington, Kids World's Adventures Team and the characters will guest star in this film.