A good supply of corn
Briggs tells Mary Bee that the mules will never make it to the river without a good feeding of corn. I don't recall them stopping anywhere to rest and feed their animals, or any dialogue to suggest that they had.
Hi, Bob.
Just because we don't see it doesn't mean it didn't happen. It's to be assumed that since it was mentioned it was taken care of, as the animals didn't die. It's hardly a crucial plot point that needs to be dwelt upon or overly explained, a passing reference does the job.
"Your mother puts license plates in your underwear? How do you sit?!"