"The last to hatch among his siblings and the smallest, 11-year-old Arlo has yet to make his mark on his family’s farm. Though he is eager to help out with chores, this sheltered Apatosaurus just can’t seem to get past his fear of everything. So when Arlo falls into a river and finds himself swept hundreds of miles away from home, he’s forced to face his fear for the first time in his life, braving the harsh, untamed wilderness and a long, arduous journey home. Along the way, Arlo develops an unlikely friendship with a human boy named Spot who helps him realize he is capable of much more than he ever thought."
- Lucas Neff was originally cast to voice Arlo. However, following the director change and revamping of the film, he was replaced by Raymond Ochoa.
- An early report in June 2013 said that the name of the protagonist dinosaur was "Jacob" (pronounced "Yacob"). This was not supported by subsequent report, and the official announcements at D23 Expo 2013 called him "Arlo".
- Concept art released before the replacement of Bob Peterson by Peter Sohn depicts Arlo as much larger than he appears in the final film. He also has blue eyes instead of amber, as in his final form.
- Arlo is the youngest protagonist of a Pixar movie.
- He is also the first Pixar protagonist to have a parent death in his feature film.
- A toy Arlo can be seen on the floor of one of the scare simulators in Monsters University.
- In Inside Out, Riley has a memory of when she and her family look at what appears to be the Cabazon Dinosaurs, and the dinosaur which their car accidentally runs into resembles Arlo.