First, you no longer need a CCW permit to carry a firearm. However, if you plan to carry out of state, realize that only some states honor a Missouri CCW; plus, you'll need to know the rules where you can carry, permit or not. Get all the info here http://batescountynewswire.blogspot.com/2016/12/permit-less-carry-starting-next-week-in.html
Second, fighting/bullying has now been upgraded from a misdemeanor offense to a felony, which can affect punishment for school age children and include area off campus as well. The new law includes situations outside of school as well, including a bar fight between two adults. More info is available here http://batescountynewswire.blogspot.com/2016/12/bullying-becomes-criminal-offense-in.html
And thirdly, if you're caught carrying marijuana, the rules have also changed. The new legislation is aimed at lowering the penalty if you're a first time offender caught with a small amount. In short, if you're caught with less than 10 grams you'll be charged with a Class D Misdemeanor, up to a $500 fine and no jail time. Review all the current Missouri laws related to marijuana here http://norml.org/laws/item/missouri-penalties-2