Other mistake: The Lassiter brothers have kidnapped a judge and a posse is searching for them. One of the men says they should quit for the day because "it's almost sundown." Judging by the shadows of the men, their horses and nearby trees, the time appears to be around 1 PM.
Factual error: "Bonanza" is set in the 1860s and the Pony Express mail service operated from 1860 to 1861. In this episode, Curtis Wade and his partner set up a Pony Express office in Virginia City and begin hiring riders. Wade tells them that the job will not be easy, adding, "I won't be giving you sweet cakes and cotton candy." Cotton candy, originally called "Fairy Floss," was invented in 1897 by William Morrison and John Wharton.
Continuity mistake: Near the start, the sarge orders the men to prepare to mount up, the soldiers walk over to the horses, and are ordered to mount. The soldier right behind the main characters starts to mount but has trouble and falls back down. Then they go to a wide angle shot and everyone is mounted.