#17 In the Pixar short Boundin', a Model T is seen driving up a hill backward. This is because Model T's relied on gravity to supply their engine with fuel, and driving up a steep hill could cause the engine to stall. The solution, if you had to drive up a steep hill, was to drive up in reverse.
#21 In Luca, the first time Luca stands on land he exhibits a medical finding called Gower's sign. Classically seen in patients with muscular dystrophy, it is due to a lack of strength in the hip and thigh muscles causing the patient to "walk" up their body to stand from a seated position.