Yes, but not really. They have "agricultural checkpoints". These are really just an annoyance for most people and isn't designed to stop anything other than people bringing in unauthorized plants, wood, or any other material that might host some kind of invasive insects that would be a danger to California's agriculture.
However, members of the California DOJ routinely drive through parking lots of sporting goods stores on the Nevada side and note California license plates to be pulled over and checked later when that vehicle is back in California. I ran into one of them at the Cabela's on 80 just outside Reno. He was parked behind my jeep and got real interested when he saw the boxes of ammo I was loading in the back. Unfortunately for him, I wasn't going back into California just yet.
They do the same thing for "illegal" fireworks. The only fireworks allowed in California are know as "safe and sane". Nothing airborne or exploding is allowed. Basically the just allow fountains and confetti cannons. There is a major pyrotechnic wholesale shop in Pahrump, NV. All this week, my local pyro page has been blowing up about plainclothes officers staking out the place and radioing license plate numbers to CHP officers waiting on 178. Ironically, Californian's like fireworks more than anybody else I've ever seen. The 1 year I spend here on the 4th, it was really like a warzone. Every other house had an assortment and hearing the explosion's echoing off the townhomes and apartments was unreal. The only downside is, people here don't reserve this activity for holidays. You'll hear them once a week throughout the year and this time of year, they'll start shooting them off every night starting around the end of may when the High Schoolers graduate.
