In every episode each character who wore a gun had a pistol belt with no loops for bullets. The show took place during the Civil War. Pistols were cap and ball, did not use metallic cartridges. Thus no bullet loops.
Actually, even though the belts had no loops, the pistols they carried were definitely metallic cartridge weapons. Ben carried a Remington Model 1875 Army revolver, and Adam, Hoss, and Little Joe all carried Colt Model 1873 Single Action Army revolvers. They can all be seen reloading cartridges into their weapons in numerous episodes.
During the first season opening credits, the Cartwrights can be seen galloping on horses on a dirt road that contains an unmistakable set of tire tracks from the truck carrying the camera in front of them.
The story of Bonanza starts in 1859 Nevada but the clothing worn by the cast is invariably 20th century . For example belt loops did not appear on men's trousers and jeans until many decades later.
Floor model wheel slot machine in saloon was not built until 1896.
Despite the fact that several main characters are shot and wounded several times over the course of the series. No bullet scars are visible when they are showed partially without clothes on.
The majority of male characters were clean shaven. Not only was this unlikely due to a lack of running water, it was also not the style for that era.
The hairstyles worn by all characters were those of its 20th century filming era, rather its 19th century setting.
The trips to Virginia City and back would take 8-12 hours as both it and the Ponderosa are located in the mountains south of Reno, NV. Given the heavy snows experienced at Lake Tahoe, such trips would be nearly impossible in the wintertime. There wouldn't be any quick trips into town.