In the TV episode, The Brave Longneck Scheme, when the gang are practising their plan to scare Rhett, on the second run Cera instructs Littlefoot to run to her. Lo and behold, in his stride he trips on something and ends up bowling into the rest of the gang who are "fleeing" from Chomper. Also, in LBT 7, Petrie falls backwards and rolled down a hill when Cera confronts him about Pterano wanting to know about the Stone of Cold Fire's location. He doesn't "trip" exactly, he kinda just falls over.
Those are two examples I can think of...