Joe tells Lotta his mother's name was Felicia. This is changed in later episodes to Marie.
The real Lotta Crabtree was born in 1847. "Bonanza" is set in 1859, when Lotta would have been 12 or 13 years old.
When Ben and the boys chase Lotta's carriage, a wheel falls off and the carriage continues for several feet before stopping. Later Hoss lifts the rear axle to look at the damage. There are no drag marks on the ground either under or behind the carriage.