Lamont returns home shortly after Norman, his replacement, exits the scene. He asks Fred "who is that guy I saw leaving?" A few minutes earlier, Fred made a big deal out of Norman using his truck, but when the door is opened (as Lamont enters the house) we can see the truck is still parked where it usually is. It should not have been visible in that scene, since Norman had driven it away.
When Norman doesn't return with the pickup in a reasonable time, Fred calls the police to report it stolen. He refers to it as a red 1952 pickup, but the pickup used in the show was a 1951 model.