Stupidity: Jeff should have just locked Red and his crew in the cellar using the key that Arlene used to open it. Instead he barricades it just so Billy could ultimately get access to it. Had Jeff locked it with the key and then taken the key with him, Billy wouldn't be able to free them. Jeff could have then just called the cops and told them where the kidnappers were contained, and then maybe later Billy could just get arrested.
Stupidity: Red and his gang have a barn full of stuff and talk about other couples and people they have kidnapped, robbed and probably killed. This indicates they have been in the "game" for a long time and been successful to avoid capture this long yet when Kurt Russell didn't want to get in the car, instead of cutting their losses, they went along with kidnapping his wife and initiating the whole ruse of her never getting in Reds truck which is what led to their downfall. Someone with the experience of this that Red has should know not to take such a big risk with a complicated story.