Speed is nervous at the end because he doesn't seem to have the Improvised Landing stunt prepared...
Rattlesnakes need to be statted in 2nd ed.
In a cowboy setting, there should probably be rules about spooked hosses -- that is, horses. If a horse is spooked, it's going to make morale saves in every encounter at a -2 penalty until an animal trainer spends time with it (or maybe a Cowboy with a Calm Hoss stunt).
(Scans courtesy of Digital Comic Museum)