Beyond the Point of Stopability
Running downhill is fun, it gives added super-speed that could not be acquired otherwise. There is a point where your legs seem to be moving on their own, you are basically falling in an upright position and there is no stopping you, you have gone beyond the point of stopability.
Also the third frame with Wally falling straight down from an object that is flying forward based on his forward momentum is bold demonstration that this comic will not be intimidated by actual physics. 😉