The cavalry troop is wearing post-Civil War uniforms.
The post/ fort that the wagon train heads to after meeting the cavalry is constructed using long logs for the walls and buildings. Yet the country they are travelling across is wide open grassy plains with no tree cover at all. There is no way such a post/ fort could have been built at that location.
The cavalry troop heading back consists only of mounted troopers. For such a long journey, the troop would at the least have one wagon of supplies for catering, and perhaps one for tents as well some spare horses.