Goofs

When Tuck illicitly purchases the Mini-14 for Jonah, he is given a form to fill out (presumably the ATF Form 4473 used when conducting the background check required for all gun purchases from a dealer). After filling it out, the manager points out that Tuck checked the box declaring he was buying the firearm for someone else (straw purchase), and directs him to check the correct box before he gives him the weapon. No gun seller, much less the manager of a gun store would coach a buyer to change a disqualifying answer on a 4473, or allow the transaction to proceed after the buyer has just admitted to attempting to straw purchase a firearm (a felony)

When Tuck purchases the Mini-14, the clerk asks if he'd like a "high capacity magazine" to go with it. Later, a 20-round magazine is shown which is smaller than the standard capacity magazine included with the rifle.

The the factory standard capacity magazine for the Mini-14 is 30 rounds. "High capacity magazine" is a generally pejorative political term used by people wishing to miss-inform the public and thus is rarely used by gun owners.

Sam is in no legal position to request "back" the money that was his mother's because she was the signatory of the contract with Marty and the money came from her account. Any compensation between Marty and Sam would have to be part of any settlement.

The rifle Jonah Byrd buys is a Ruger Mini-14. When he fires it, it seems to fire full auto. Although a fully automatic (Class III) weapon would have cost tens of thousands of dollars and take up to a year of background checks and interviews to obtain from a specialized dealer, the rate of fire shown is far below the Mini-14's cyclic it would have been more believable had they shown him practicing bump fire. It is a one trigger pull one shot firearm. This is the episode where you realize they have no idea how guns work.