Dude, you have to learn googling skills. This stuff pops in by typing 'filmmaking laws'.
You must have written permission to use content that is not yours.
Everyone seen in the film must be under contract (yes, even people in the background that are recognizable).
When filming, you have to have permission to shoot in the location you are shooting in.
Do not show or talk about phone numbers that actually exist, it's considered invasion of privacy (same goes for addresses, credit card numbers, etc.)
Recognizable products and brands must be allowed by the owner to be seen in the film.
Except as covered by Fair Use laws
You cannot plagiarize large portions of a past piece of work you are not allowed to use.
If an actor is part of a union, you must meet requirements.
Union regulations are the actor's problem, not yours.
You may not harm animals.
You should and cannot feature weapons in public. Scenes could be mistaken for actual fights or crimes.
You can as long as you are in an "open carry" state. You should not without police presence.
It is smart to copyright your film.
Your film, as an original work and piece of intellectual property is copyright at the moment of it's creation. It is smart to register your screenplays with the copyright office or WGA.
You may not say a story is based upon true events, and twist what happened. For example, showing someone who was found innocent as a murderer.
Filmmakers should get insurance.
Good advice, but not required any any specific law that I know of.
Those are some basic ones, and are not black and white. Some of them you can twist and alter. Sometimes you can shoot without insurance, or go guerrilla and shoot illegally.
Shooting guerrilla style is not always (or usually) against the law unless you are shooting in an area that has a local ordinance requiring permits for any commercial film production. Strictly speaking, engagement videos and video of your kids playing at the park are shot guerrilla style.
Google. It's your friend.
