As Wile E. holds out his arms to catch the box, Road Runner runs by and taunts him long enough so that he forgets about the descending package which lands on top of his head.
For good measure, the Road Runner paints a giant boulder and pushes it off the cliff; it lands on top of the unsuspecting Coyote.
Back at his chemistry lab, Wile E. adds a chemical to a beaker filled with blue liquid, creating a bounceable substance.
He bounces off the ground and high into the air to get back up to the top of the canyon, but part of the rubber suit gets caught on a branch and the whole thing tears off the Coyote.
After crashing into an "Acme Garment Co." truck and exiting out its back, he sees the Road Runner head into a train tunnel and follows him in.
The train tunnel gag is recycled from earlier Bugs Bunny cartoons, Hare-Less Wolf (1958) and Bill of Hare (1962).