While re-reading my bareback scene, I realized that Shelby had told the wrangler applicants that she didn't expect them to turn into Stacy Westfall, who is known for her amazing bridleless bareback riding skills.
However, I did manage to forget to have Shelby give them bridles to ride with. They arrived at the arena with their horses in tow, a few sentences later they swung their reins (apparently they were imaginary since Shelby forgot to give them bridles) over their horses' necks and rode into the arena. Oops. I did manage to get all of the wranglers into helmets, though (surprise, surprise, Heidi and Julie - and you thought I'd never use my helmet again).
The good news is that when I realized my mistake and fixed it, I'd added a couple hundred words to my word count. And Shelby's wranglers don't have to ride like Stacy Westfall.