Spot finds four other humanlike creatures and goes to them. Arlo is standing several feet in front of them. He begins to push some dirt by using his nose. A close-up then shows him using his nose to draw a circle around the five others but he is standing much too far away to be able to do this.
Arlo is surrounded by a large herd of gopher-like creatures. When they begin to crawl up his legs, he flings them off and begins to run. In the long shot which follows, the creatures are no longer close together but are scattered.
A heavy rain is falling as Arlo and Spot are trapped in a rushing river. During close-ups of Arlo, the rain is falling at a sharp angle to the right. During close-ups of Spot, the rain is falling at a sharp angle to the left.
The mark made by Arlo doesn't correspond to how he placed his paw in the previous shot.
Although Thunderclap is a Nyctosaurus, he is depicted with teeth and very sharp wing claws, and he's also depicted with feet that are pretty good for grasping things. However, the real animal lacked any teeth nor didn't have any sharp wing claws and its feet weren't strong enough to grasp stuff.
In the film, the T-Rexes gallop although in real life they would have run more like birds. However, the T-Rexes are cast in the film as cowboys riding herd on their longhorns. The animators clearly used galloping to fit this trope. Humor is added by the straight posture of the T-Rexes and their short arms which mimics the role of riders holding reins while atop horses (and how many children act while playing 'cowboy').
Arlo and his family are Apatosaurs. This is according to promotional materials; this name is never spoken in the film. Butch recalls an encounter with a Stegosaur, which he describes correctly. Both Apatosaurs and Stegosaurs went extinct before the point of divergence of this alternate history. (The Apatosaur goof could be mitigated by saying that Apatosaur is being used as a generic term for Sauropods, but the same cannot be said of Stegosaurs.)
Apparently Arlo and his family live during the same time as the pack of Tyrannosaurus Rexes but in reality Apatosaurs lived in the Jurassic period millions of years before the Tyrannosaurus Rex appeared. Plus other dinosaurs of the Cretaceous period can be seen, meaning Arlo and his family should not have existed.