As long as the tequila doesn't get too hot and is unopened, I don't think you would have problems driving it back to CA in your car's trunk. I've brought wine back to AZ from Vegas.
A few years ago, I remember all cars being stopped for immigration check points along I 8. At one of them, the dog got excited and they pulled the car in front of me over. I wasn't able to hang out and find out why. I don't recall anyone asking about anything in my car on last Sept's road trip, Phx, Lake Tahoe, Sacramento, Reno, Las Vegas and back to Phoenix, nor do I remember anyone asking about adult beverages when they stopped all cars on both sides of Hoover Dam.