Wyoming license plates have stacked numbers 1-23 on the far left that represent the 23 counties in the state. Wyoming residents can tell from what part of the state a vehicle is from, something that everyone in Wyoming knows. Great detail for directors to put 24 on the license plates of all the cars in the series as a made up county.
Sheriff Walt Longmire (Robert Taylor) carries a 1911, .45ACP Colt Government Model with custom stag grips for his duty sidearm. Unlike most who choose to carry the M1911, Walt chooses to carry in Condition 2 (mag inserted, round chambered, hammer down) This isn't necessarily bad production/directing. There was a time when this was the acceptable method of carry, although now, most M1911 users do not recommend for safety reasons, instead choosing Condition 1 (Mag inserted, round chambered, hammer cocked, safety on) which is the way the pistol is designed to be carried.
The series is based on taking place in Wyoming, but it is filmed in and around Santa Fe and Las Vegas, N.M. The sheriff's office is on the plaza in Las Vegas at 1811 Hot Springs Blvd., just across from the famous Plaza Hotel. Many scenes are also filmed in Pecos, N.M. and in the Pecos Wilderness north of the town of Pecos.
Carrying his sidearm the way he does, round chambered and the hammer down, makes a lot of sense for two reasons. From a theatrical standpoint you get the effect of his cocking the hammer. It also agrees better with his character who "sometimes likes to think before he talks (acts)" by making discharging his weapon a more deliberate act.
The scenes for Longmire's cabin are filmed in the Valles Caldera in the Jemez Mountains of New Mexico. The caldera is a 14 mile wide volcanic crater. It is now a national preserve. Several Westerns including The Missing and Lone Ranger have used this location.