Continuity mistake: When Jax and his crew meet up with a Hispanic gang to sell them guns and are outnumbered, they run in the station wagon. The run the station wagon through a gate and roll it, destroying the front end, but magically the station wagon's front end appears with little damage afterwards.
Revealing mistake: In the scene where Jax and crew go to help escort Tig after he ran into Laroy with a car at the cafe, they get caught in a traffic jam and have to drive on the breakdown lane. Jax shoots at the SUV with Laroy and kills the driver and the car slams into a car that is stuck in traffic, but there is no one sitting behind the wheel of that car.
Other mistake: When the Sons are meeting with the Irish, Jax rides up on his motorcycle late to the meeting. He removes his helmet and his hat is backwards, revealing the Sons logo. In the next shot, when he's shaking the Irishman's hand, it's forward, then in the following cut back, it is backwards again.
Factual error: A BMW is towed to the shop with a buck (male deer) implanted through the windshield - the back half protrudes from the hole in the glass. An employee uses a chainsaw to remove the carcass in pieces. Later, the head of the buck is pulled from a box, and is seen to still have its sizable antlers. These antlers would not have remained attached as the head passed through the windshield - they would have snapped off. And even if they had not broken off, the windshield's damage would have been significantly different to account for the antlers passing through it.